USB Stack crashes from time to time

Hello There,

got a 11.2 64 bit install on nVidia MCP78S (asus m3n8200) with phenom 2 x3

i run a VM on this machine with 2 usb devices connected and passed through correctly (usb dongle and rs232 adapter).

from time to time my VMWARE freezes (virtualbox also does!) and i found out that a usb device disconnects for some reason driving the VM to become zombie.
lsusb also hangs.

i also tried fedora 12 64 bit, with the same result GRMPHL

this is what the log says:
Apr 22 20:03:19 localhost kernel: <ffffffff812fe91c>] usb_kill_urb+0xb3/0xd1

is there known any issue/incompatibilites?

would really appreciate any useful help

regards,

martin

by the way: on my old system (fedora 3) the same usb devices work fine within a vm…