Okay, I had Coppermine installed using Fantastico on my Host's CPanel. It was working fine and everything. Then we exceeded our bandwidth for the month and when we came back we got 500 Errors in the image gallery, I mean we can't even look at the front page it's so bad.
1) Fantastico is using a modified version of Coppermine and that has been known to give problems - please search the boards for Fantastico
2) 500 Errors are server configuration errors usually nothing to do with Coppermine code - ask your host as to what messages are getting recorded in the error logs.