I agree with you that the only sure way of fixing this is to erase the hard drive. I am running Tiger, as I have not upgraded and do not intend to until I buy a new computer--probably next year.

Big problem for me is that I don't seem to be able to find my install disk. After 2 moves it's probably buried deep in storage. I'm guessing there's no way for me to reinstall without the disk. Any ideas if there's a next-best approach worth trying, short of taking hours to dive into my store room?