I need help. When I try to compress game data it tells me failed to compress... Please help!

The only thing i can think of is that some of your game data has been corrupted. But that alone is a long shot.

For problems like these, try uninstalling and reinstalling the program, if you cant think of anything else.
Unless anyone else here has a suggestion, the people here may be able to help you a bit better with this error.

http://www.rmxp.org/forums/