Well, after spending a frustrating hour not having coherence mode, I have it back again. So, I thought I would be a good guy for once and post my "fix" in case it happens to anyone else. What was wrong: Coherence mode was not available. The error message said to reinstall parallels tools. That did not fix the problem. What I had done: Well, I knew what I had done differently this morning. I updated Windows XP using Microsoft Update and checked everything without really reading. One of the updates was to the mouse driver. It installed an IdeaCom TouchScreen HID driver. That turned out to be bad. But, I couldn't just uninstall the driver - it kept coming back after the next reboot! What worked: After reading several posts from other frustrated users with similar issues, I found one from 2006 that recommended reinstalling the keyboard! Genius! That finally got rid of the stupid IdeaCom driver for good. I don't know why a keyboard driver impacted a mouse driver, but there you go. After a reboot, all was well except Coherence was still not available. One more dive into the Device Manager, and I discovered that the mouse driver was now just a PS/2 driver. I switched that to the Parallels driver, and - voila! Coherence! Recap: MacBook Pro + Parallels 4.0.3810 + Windows XP SP3 + keyboard driver: PC/AT Enhanced PS/2 Keyboard (101/102-Key) + mouse driver: Parallels Mouse Synchronization Device = Coherence Hope this helps someone!
