I upgraded my Mac to OS X 10.7 Lion the other day and found that USB devices no longer worked.
They appeared in device manager saying they could not start.
I found the following fix on the VMware forums :
You can check if you have non standard permissions by opening a terminal and running:
ls -ld /
You should see output like this:
drwxr-xr-x 53 root wheel 1870 Aug 4 12:43 /
If the permissions are different than above you can reset them using the following steps (for Fusion 3.1.3):
In a terminal (/Applications/Utilities/Terminal.app)
chown root:wheel /
chmod 755 /
Start Fusion and try connecting a USB device.
Source : VMware Forum