UMDGen - buffer overrun detected

OK so I have a number of ISO files, most load fine in UMDGen and thus play fine on the psp, however, some don't show on the PSP, so, on the reccomendation of a friend I put them in to UMDGen to see if it detected them, most times it said 'not a valid file, can try to read it' and it just closed, and sometimes I get the buffer overrun detected - this makes me think its something connected to UMDGen and not the iso, but then a different ISO will load fine!

SO.... these 'damaged' ISO files - I was basically about to delete them, thinking they are useless, however, is there anything I can do with them to try and rectify them?

Well, the ISO uses Standard iso9660 format, so try opening it somewhere else (MagicISO, PowerISO)

Also, try re-installing UMDGen. It should be 4.0.

Well I can open the image in say ImgBurn, but it still doesnt work in the psp, I guess I should try redumping it again... just have to get a few games back off my brother who doesn't have a CFW enabled psp :p