VMware, Vista and VPN

I have been battling a strange problem plaguing my Windows Vista virtual
machine. I need access to a Windows machine in order to connect to my
employer’s VPN from home. I have Vista installed in a VMware 5.5 virtual
machine with the requisite VPN software on a Fedora 7 host. So far so
good. The problem is the Vista clock is running about twice as fast as
it should. A minute is elapsing in Vista in about 30 seconds of wall
clock time. As the clock gets further and further out of sync, the VPN
has problems keeping the packets in order and eventually gives me the
boot. That makes working on the VPN rather difficult. Luckily, fixing it
is easy. All that I had to do was disable the USB controller on the
virtual machine. The USB polling causes the clock interrupt to fire more
often than it should, and that is why the clock is running fast.