I just recovered from the same problem after installing Free Tools, by deleting it from Extension Manager and restoring my en_US folder via Apple's Time Machine (whew)! I did delete the extensions the install instructions said to delete before installing, but I think I may have missed Google Tools.
Anyway..... just as a precursor to ultimately installing Free Tools, after finding out it is ok and all working by some post saying so in this thread, I did the recommended procedure above about resetting things in the WA Prefs and deleting the MacFileCache.dat file ......
So right now.....
....I'm now monitoring this thread to see how this gets resolved before daring again.
For the record, I'm using OS C 10.6.8 w/ DW 5, and have most of the old Super Suite extensions (haven't yet upgraded to DE or DB but hope to soon).
So someone please let me know if these problems I read about, and encountered myself as well, have been resolved.