I've been freezing a lot more lately, so I looked up this:

http://community.us.playstation.com/message/695272

One of the options in safe mode is "Restore File System". This removes or fixes any corrupt files found in your system, and doesn't affect the files you've put on your PS3 yourself. I thought it might help those with freezing issues, may not though, but worth a try. Mine is doing this at the moment, so I'll report back.