I was getting error messages about syntax errors in files when trying to upgrade Parallel Tools. The above was very useful in finding a solution though I had to do some extra things to get it to work, using Windows XP:
1. In windows, go to Control Panel and from Add/Remove Programs remove Parallel Tools. It will probably ask you to restart to complete the action
2. Back in Windows, go to My Computer, C Drive, Program Files folder, and if there is still a Parallels Tool folder there (Windows doesn't clean up after itself very well) delete it
3. Quit Windows. From the Parallels Tool menu bar in OSX, go to Actions and then click Prepare Parallel Tools Upgrade. Wait for a confirmation message to appear
4. Log back into Windows. Go to My Computer and find your CD-ROM drive - Drive D probably. Right click on it and then select Explore. Find the Tools set-up.exe file and double click it. In my case then installation worked.
Hope this helps someone. It's a bit fiddly but it is worth it - Coherence is just mind-blowing.

Click to expand...