PSP can't load ISO games

I upgraded my fat PSP to 3.71 M33-3, and was using 3.52 M33-4, and have not been able to get these ISO files to play...

Need for Speed Most Wanted, and World Series of Poker 2. The error message I get is Game cannot start, 80020321. Any suggestions, or ideas what's wrong with it? I am completely new to this....

I can however play games that aren't in ISO format. I put the ISO files in the ISO directory on the memory stick.

Thanks!

You need to put a UMD in your PSP and it should play. But i think you can also mess with the Recovery Mode and fix it so you don't need to, but all you have to do is insert a UMD game into your PSP and the ISO should play.

Wow...so simple! Thanks, it works now

Yea it happens , the same thing happened to me and i was wondering what the deal was.