OMG! This gives me a crazy idea to suggest to everyone in this thread having problems with their printers. Crazy, but rather safe, and it could do the trick...
0. Make sure NO USB device is connected to Parallels Desktop to the moment. Also make sure you have closed all applications actually running in Windows and saved all your data.
1. Go to Start->Control Panel->Performance and Maintenance->System
2. Select "Hardware" Tab and click "Device Manager".
3. Double-click "Universal Serial Bus controllers" to expand the group.
4. Now, for each device in this group, right-click it, and select Uninstall in the pop-up menu. Click "OK" when the warning appears. You will end up having all the group disappeared.
5. Reboot Windows.
6. When rebooted, wait for some time. Windows will find some devices. Let it install them.
7. Now, re-check your printer to see if it works now. Please report your findings here.
Last edited: Mar 29, 2007