I just noticed this 'regression?' on a 32-bit system running the prior 2.6.32.23 [meaning, I observed 'whups, it's broken again' on a machine that had been running that kernel for days or weeks] and an update to 2.6.32.24.25 did not immediately resolve it. The majority of USB devices, including the one I was trying to use [HP OfficeJet v40, scanner component via scanimage backend in gscan2pdf] are connected to the ports on the system's SB600 southbridge. Using the 'unbind' trick detailed above for the EHCI controller did not help. This configuration must have been working at some point, or we would have noticed earlier. I was at a loss after a few reboots until I tried a fully cold boot [as opposed to use of both soft-reboots and the reset switch], at which point the hardware is now 'happy' under 2.6.32.24.25 (and presumably would be under the prior kernel as well). Accordingly, please remember to give that a shot... and do mention if it's the only thing that works, as I suppose there could be an issue with the state 'warm' hardware comes up in. After the working boot, there is still with the following noise in dmesg, but the HP on 9-2 has 'always' been petulant like this: [ 60.184052] usb 9-2: new full speed USB device using ohci_hcd and address 10 [ 60.364041] usb 9-2: device descriptor read/64, error -62 [ 60.648033] usb 9-2: device descriptor read/64, error -62 [ 60.928045] usb 9-2: new full speed USB device using ohci_hcd and address 11 [ 61.108080] usb 9-2: device descriptor read/64, error -62 [ 61.392054] usb 9-2: device descriptor read/64, error -62 [ 61.672044] usb 9-2: new full speed USB device using ohci_hcd and address 12 [ 62.080046] usb 9-2: device not accepting address 12, error -62 [ 62.256040] usb 9-2: new full speed USB device using ohci_hcd and address 13 [ 62.664064] usb 9-2: device not accepting address 13, error -62 [ 62.664101] hub 9-0:1.0: unable to enumerate USB device on port 2 [ 74.084164] usb 9-2: new full speed USB device using ohci_hcd and address 14 [ 74.268064] usb 9-2: device descriptor read/64, error -62 [ 74.552063] usb 9-2: device descriptor read/64, error -62 [ 74.832051] usb 9-2: new full speed USB device using ohci_hcd and address 15 [ 75.012052] usb 9-2: device descriptor read/64, error -62 [ 75.300061] usb 9-2: device descriptor read/64, error -62 [ 75.568061] usb 9-2: new full speed USB device using ohci_hcd and address 16 [ 75.976043] usb 9-2: device not accepting address 16, error -62 [ 76.152061] usb 9-2: new full speed USB device using ohci_hcd and address 17 [ 76.560033] usb 9-2: device not accepting address 17, error -62 [ 76.560069] hub 9-0:1.0: unable to enumerate USB device on port 2 [ 117.306043] usb 9-2: new full speed USB device using ohci_hcd and address 18 [ 117.488058] usb 9-2: device descriptor read/64, error -62 [ 117.772052] usb 9-2: device descriptor read/64, error -62 [ 118.052056] usb 9-2: new full speed USB device using ohci_hcd and address 19 [ 118.232054] usb 9-2: device descriptor read/64, error -62 [ 118.520081] usb 9-2: device descriptor read/64, error -62 [ 118.800057] usb 9-2: new full speed USB device using ohci_hcd and address 20 [ 119.209054] usb 9-2: device not accepting address 20, error -62 [ 119.385055] usb 9-2: new full speed USB device using ohci_hcd and address 21 [ 119.796072] usb 9-2: device not accepting address 21, error -62 [ 119.796111] hub 9-0:1.0: unable to enumerate USB device on port 2 [ 311.280039] usb 7-1: new full speed USB device using ohci_hcd and address 2 [ 311.451784] usb 7-1: configuration #1 chosen from 1 choice ... [ 315.106835] hub 7-0:1.0: port 1 disabled by hub (EMI?), re-enabling... [ 315.106849] usb 7-1: USB disconnect, address 2 ... [ 321.920040] usb 9-2: new full speed USB device using ohci_hcd and address 22 [ 322.132562] usb 9-2: configuration #1 chosen from 1 choice Note that nothing?, except possibly a USB KVM, is connected to bus 7. Bus 009 Device 022: ID 0a12:0001 Cambridge Silicon Radio, Ltd Bluetooth Dongle (HCI mode) Bus 009 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 008 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 007 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 006 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 004 Device 002: ID 03f0:0f11 Hewlett-Packard OfficeJet V40 Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 003 Device 003: ID 046d:c404 Logitech, Inc. TrackMan Wheel Bus 003 Device 002: ID 10d5:0116 Uni Class Technology Co., Ltd Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 008: ID 062a:0000 Creative Labs Optical mouse Bus 001 Device 007: ID 0764:0501 Cyber Power System, Inc. CP1500 AVR UPS Bus 001 Device 006: ID 058f:6362 Alcor Micro Corp. Hi-Speed 21-in-1 Flash Card Reader/Writer (Internal/External) Bus 001 Device 005: ID 05e3:0606 Genesys Logic, Inc. USB 2.0 Hub / D-Link DUB-H4 USB 2.0 Hub Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub ... I also discovered the following, which may explain why gdm seems to hang without displaying the user-picker every couple boots [observed with both recent kernels and probably a few others] (where Xorg works but the greeter never fully loads): daemon.log:Aug 15 22:17:16 localhost gdm-simple-greeter[1665]: devkit-power-gobject-WARNING: Couldn't enumerate devices: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken. So flaky USB can stall gdm from ever getting around to displaying the user-picker. Yay! ... Meanwhile, the full cohort of USB controllers on this system: 00:13.0 USB Controller: ATI Technologies Inc SB600 USB (OHCI0) (prog-if 10) Subsystem: Foxconn International, Inc. Device 0c8d Flags: bus master, 66MHz, medium devsel, latency 64, IRQ 16 Memory at fe8fe000 (32-bit, non-prefetchable) [size=4K] Kernel driver in use: ohci_hcd 00:13.1 USB Controller: ATI Technologies Inc SB600 USB (OHCI1) (prog-if 10) Subsystem: Foxconn International, Inc. Device 0c8d Flags: bus master, 66MHz, medium devsel, latency 64, IRQ 17 Memory at fe8fd000 (32-bit, non-prefetchable) [size=4K] Kernel driver in use: ohci_hcd 00:13.2 USB Controller: ATI Technologies Inc SB600 USB (OHCI2) (prog-if 10) Subsystem: Foxconn International, Inc. Device 0c8d Flags: bus master, 66MHz, medium devsel, latency 64, IRQ 18 Memory at fe8fc000 (32-bit, non-prefetchable) [size=4K] Kernel driver in use: ohci_hcd 00:13.3 USB Controller: ATI Technologies Inc SB600 USB (OHCI3) (prog-if 10) Subsystem: Foxconn International, Inc. Device 0c8d Flags: bus master, 66MHz, medium devsel, latency 64, IRQ 17 Memory at fe8fb000 (32-bit, non-prefetchable) [size=4K] Kernel driver in use: ohci_hcd 00:13.4 USB Controller: ATI Technologies Inc SB600 USB (OHCI4) (prog-if 10) Subsystem: Foxconn International, Inc. Device 0c8d Flags: bus master, 66MHz, medium devsel, latency 64, IRQ 18 Memory at fe8fa000 (32-bit, non-prefetchable) [size=4K] Kernel driver in use: ohci_hcd 00:13.5 USB Controller: ATI Technologies Inc SB600 USB Controller (EHCI) (prog-if 20) Subsystem: Foxconn International, Inc. Device 0c8d Flags: bus master, 66MHz, medium devsel, latency 64, IRQ 19 Memory at fe8ff000 (32-bit, non-prefetchable) [size=256] Capabilities: Kernel driver in use: ehci_hcd --- 02:00.0 USB Controller: NEC Corporation USB (rev 41) (prog-if 10) Subsystem: Device 3083:0035 Flags: bus master, medium devsel, latency 64, IRQ 20 Memory at febff000 (32-bit, non-prefetchable) [size=4K] Capabilities: Kernel driver in use: ohci_hcd 02:00.1 USB Controller: NEC Corporation USB (rev 41) (prog-if 10) Subsystem: Device 3083:0035 Flags: bus master, medium devsel, latency 64, IRQ 21 Memory at febfe000 (32-bit, non-prefetchable) [size=4K] Capabilities: Kernel driver in use: ohci_hcd 02:00.2 USB Controller: NEC Corporation USB 2.0 (rev 02) (prog-if 20) Subsystem: Device 3083:00e0 Flags: bus master, medium devsel, latency 64, IRQ 22 Memory at febfdc00 (32-bit, non-prefetchable) [size=256] Capabilities: Kernel driver in use: ehci_hcd [The only device on the NEC card is the Bluetooth dongle, though I can't tell if that's having other problems now or just running into the old 'Bluetooth UI fails if dongle comes up at too high a device number' bug or such. dmesg and lsusb seem to find it okay.]