Tried the Evaluate Tree Consistency, but nothing happened.
it shows its summary in the status bar -- if it didn't complain then it didn't find anything wrong.
try this -- do a save as, and specify a simple file name in some path under your MyDocuments.
then after it gives you the error -- go look in that path and see if it created any file at all.
other than that.. exit the program, restart it, and try another save as and let me know if it's always giving that error.
i can try to build a special debug version to help us pinpoint where the problem is..
if it gives that error even after you restart, then it sure sounds like its having some trouble getting permission to write the file.