I'm having the same problems. Here's my output to those last two commands:

~# dmidecode -t bios | head -8
# dmidecode 2.9
SMBIOS 2.3 present.

Handle 0x0000, DMI type 0, 20 bytes
BIOS Information
    Vendor: Dell Computer Corporation
    Version: A17
    Release Date: 06/29/2005


~# dmidecode -t system | head -8
# dmidecode 2.9
SMBIOS 2.3 present.

Handle 0x0100, DMI type 1, 25 bytes
System Information
    Manufacturer: Dell Computer Corporation
    Product Name: Inspiron 600m
    Version: Not Specified


On Sun, Jan 11, 2009 at 9:00 PM, nanotube <email address hidden> wrote:

> Here's my dmidecode info, in case it's needed. Again, this is a dell
> inspiron 5150.
>
> dmidecode -t bios :
> ------
> # dmidecode 2.9
> SMBIOS 2.3 present.
>
> Handle 0x0000, DMI type 0, 20 bytes
> BIOS Information
>        Vendor: Dell Computer Corporation
>         Version: A37
>        Release Date: 09/29/2004
>
> dmidecode -t system
> -------
> # dmidecode 2.9
> SMBIOS 2.3 present.
>
> Handle 0x0100, DMI type 1, 25 bytes
> System Information
>        Manufacturer: Dell Computer Corporation
>         Product Name: Inspiron 5150
>         Version: Not Specified
>
> --
> Losing keyboard and mouse control when changing screen brightness with fn +
> arrow under intrepid
> https://bugs.launchpad.net/bugs/285323
> You received this bug notification because you are a direct subscriber
> of the bug.
>
> Status in Gnome Powermanager: Invalid
> Status in Ubuntu Release Notes: New
> Status in "acpid" source package in Ubuntu: Invalid
> Status in "gnome-power-manager" source package in Ubuntu: Invalid
> Status in "linux" source package in Ubuntu: New
> Status in "xserver-xorg-input-evdev" source package in Ubuntu: Invalid
> Status in acpid in Ubuntu Intrepid: Invalid
> Status in gnome-power-manager in Ubuntu Intrepid: Invalid
> Status in linux in Ubuntu Intrepid: Triaged
> Status in xserver-xorg-input-evdev in Ubuntu Intrepid: Invalid
>
> Bug description:
> On my Dell inspiron 9300 laptop under intrepid (hardy did not have this
> problem), when I type FN + Arrow keys to change the screen brightness, Most
> of mouse and keyboard keys stop working.
>
> For an example : I can't type any text anywhere, ALT + F4 does not close
> any window, mouse clicks "partially" opens the gnome-panel menus, isn't able
> to close windows with the right-top x, but mouse click is still able to move
> a window..
>
> screencast :
> http://upload.leservicetechnique.com/bugs/mouse_keyboard_acpid.ogv
>
> This bug is reproducible under both metacity and compiz, and not caused by
> a BIOS password.
>
> A quick workaround to bring back things to normal is to switch to a VT and
> go back to Xorg with CTRL + ALT + F6 and CTRL + ALT + F7
>
> When changing screen brightness, I get this in Xorg.0.log :
>
> (II) AIGLX: Suspending AIGLX clients for VT switch
> (II) Open ACPI successful (/var/run/acpid.socket)
> (II) AIGLX: Resuming AIGLX clients after VT switch
> (II) AlpsPS/2 ALPS GlidePoint: x-axis range 0 - 1023
> (II) AlpsPS/2 ALPS GlidePoint: y-axis range 0 - 767
> (--) AlpsPS/2 ALPS GlidePoint touchpad found
> (II) Macintosh mouse button emulation: Device reopened after 10 attempts.
> (**) Macintosh mouse button emulation: YAxisMapping: buttons 4 and 5
> (**) Macintosh mouse button emulation: EmulateWheelButton: 4,
> EmulateWheelInertia: 10, EmulateWheelTimeout: 200
> (II) PS/2 Mouse: Device reopened after 10 attempts.
> (**) PS/2 Mouse: YAxisMapping: buttons 4 and 5
> (**) PS/2 Mouse: EmulateWheelButton: 4, EmulateWheelInertia: 10,
> EmulateWheelTimeout: 200
> (II) AT Translated Set 2 keyboard: Device reopened after 10 attempts.
> (II) Video Bus: Device reopened after 10 attempts.
>