Ok, if it's the .myi that keeps getting corrupt then that's definitely the indexes. I'd move it to 4. With 7.2 I'll be putting back the option to use the old search method if you need to search for less than 4 characters.
I'm sure you can specify a different tmp folder, but I'm not exactly sure how. Let me know when you plan on doing this, I'd like to do/check a few things before hand.
