Can't Open Final Cut - "Waveform Cache Files Folder does not have read/....

I am new to Final Cut and macs, so please bear with me.

I have created an animation in Final Cut pro (5) using stills. The project takes up a lot of space, which is why I have moved the 'Final Cut Documents' file onto my external hard drive. However, I relocated/reconnected the project files when I next opened the project and all was peachy.

Last night when I had the project open I got errors about not being able to save the project. This was my first problem, but is now insignificant compared to this new problem this morning:

I cannot open Final Cut. I have an error saying 'The Waveform Cache Files Folder does not have read/write access. Please select a new folder in the System Settings Dialog or correct the problem on disk'. Final Cut then proceeds to shut down, so I cannot change any user settings within the program.

I have made all Final Cut folders read/write as well as my external hard drive and anything else with Final Cut on it. It still presents this warning.

A final confession: last night in (I think?) User Preferences I changed some of the settings to my external hard drive (I'm not even sure what settings...I just checked boxes next to the Hard Drive and unchecked a box next to the laptop drive), hoping it would just save the project to it, rather than on my laptop. This may have contributed to this new problem...maybe not.

PLEASE HELP...this animation is due Monday.