Touchscreen: Left mouse button stays clicked and multitouch doesn't work anymore

As soon as I touch my Acer T231H multi-touch touchscreen, the left mouse button stays pressed. Reconnecting all HID devices does not release the mouse button. Only restarting lightdm (or the whole computer) helps.
But I am still able to use some applications after I touched the screen (For example Chromium and Rhythmbox). Other applications such as Nautilus on the other hand don't accept any clicks after that.

Another problem is that multitouch doesn't work anymore. While I was able to pinch-zoom in 11.10 eog I can't do this anymore in 12.04.

PS: The touchscreen is shown as "Quanta Computer, Inc. Optical Touch Screen" by lsusb.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: utouch 1.2
ProcVersionSignature: Ubuntu 3.2.0-24.39-generic 3.2.16
Uname: Linux 3.2.0-24-generic x86_64
NonfreeKernelModules: fglrx
ApportVersion: 2.0.1-0ubuntu8
Architecture: amd64
Date: Sun Jun 10 18:35:57 2012
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
LsInput: Error: command ['gksu', '-D', 'Apport', '--', 'env', '-u', 'LANGUAGE', 'LC_MESSAGES=C', 'lsinput'] failed with exit code 127:
MachineType: Gigabyte Technology Co., Ltd. To be filled by O.E.M.
MtDevices: Acer T231H: /dev/input/event12
PackageArchitecture: all
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-24-generic root=UUID=08a16439-c0ca-4f8c-b79e-cadc17aafb15 ro quiet splash vt.handoff=7
SourcePackage: utouch
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 03/09/2012
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: F2
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: Z77-DS3H
dmi.board.vendor: Gigabyte Technology Co., Ltd.
dmi.board.version: x.x
dmi.chassis.asset.tag: To Be Filled By O.E.M.
dmi.chassis.type: 3
dmi.chassis.vendor: Gigabyte Technology Co., Ltd.
dmi.chassis.version: To Be Filled By O.E.M.
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrF2:bd03/09/2012:svnGigabyteTechnologyCo.,Ltd.:pnTobefilledbyO.E.M.:pvrTobefilledbyO.E.M.:rvnGigabyteTechnologyCo.,Ltd.:rnZ77-DS3H:rvrx.x:cvnGigabyteTechnologyCo.,Ltd.:ct3:cvrToBeFilledByO.E.M.:
dmi.product.name: To be filled by O.E.M.
dmi.product.version: To be filled by O.E.M.
dmi.sys.vendor: Gigabyte Technology Co., Ltd.