Annoying Eclipse "Problem Occurred" Again

I post this so that it might help someone else in a similar frustrating state. My Eclipse 3.3 has been giving me this annoying message ever few minutes.

Problem Occurred
periodic workspace save.
Cannot find file C:\Projects\.metadata\.plugins\org.eclipse.core.resources\.projects\KB-485\1.tree

This project is a large CVS repository with over 1GB of static file content (don't ask I didn't have any involvement in the creation of the CVS module.) Recreating the project would be several hours of time pulling down the files from the network.

This error was causing me to have to click ok while trying to write code. Also, I got the same error trying to even close the project.

I fixed it by navigating to the directory in the error:
C:\Projects\.metadata\.plugins\org.eclipse.core.resources\.projects\
creating the missing KB-485 folder and creating the missing 1.tree file (just an empty file)

Then I was able to close the project and open it and the 1.tree file was overwritten and the error has been fixed.