Hi, everyone.

I've solved my own problem. Here's what I learned.

A guy named James posted his experiences with this error at:
http://hamesterrepublic.com/james/linux/

The problem is that some cache files are corrupted. If you remove these files, then you can start the Application Manager again and it works.

First, start a terminal and become root. (If you can't start the terminal and become root, then I don't know what you'll need to do. I don't believe the File Manager will let you remove the corrupted files if you're not root)

Then,

cd /var/cache/apt

mkdir bak_cache
(or whatever you want to call your back-up copy of the files to be removed).

mv *cache.bin bak_cache/

This moves the files into the back-up directory without leaving copies behind. Because the Application Manager only looks in one place for these files, it is the same as deleting them as far as the App. Manager can tell. Exit the terminal program and restart the Application Manager. Hopefully all will be well. It worked for me. If that didn't work, you can restore your files from the backups and look for another solution. Good luck!

-- Killick