Can't play ripped UMD's

[wdayglow]

I recently Instaled M33-6 on my psp slim. I've copied a umd game and my pc compressed the folder. when i extracted the folder and copied it into the iso folder in my psp it doesn't show up when i come to playing the game. If I leave the folder compressed and copy it into the iso folder it plays fine.
I then downloaded a game that when i copy it into my iso folder it doesn't show up i've tried to copy parts of the folder into the game folder and i get a corrupted data folder on my psp. Any help would really be appreciated i've been messing around with this for a few days now. My umd iso mode is selected to sony np9660
I also read somewhere it could be my memeory stick but it plays the compressed umd with no problems.

[RainMotorsports]

ISO/CSO files made from a umd go in the ISO folder ie ms0:/ISO/your.iso
Press Select when at the XMB and change the no umd driver to Sony NP9660 or M33.

EDIT - Your pc did not compress anything WinRAR and other apps can"open" iso's just copy the ISO its not a folder....