Hi, A bug was reported against qemu v1.1 in openSUSE 12.2. See: https://bugzilla.novell.com/show_bug.cgi?id=766310
I've discovered that uhci_queue_free is called with a queue that is still active. Bisecting shows that this bug was introduced in git commit id d9a528db7f2d71d92e869e20bda37774f11fbbe1. Setting the queue memory to some non-zero value before it is freed helps expose the issue. In addition to the -usbdevice tablet case reported in the bug, I also see the same problem with -usbdevice net and -usbdevice audio, while other usb devices that I tested don't show this problem. Bruce