I was still having this problem even on the latest version of pcsx-rearmed. It seems in my case it was because the PBP files were created with no compression in the PSX2PSP program. Once I re-did it with compression set to level 2 (in the options) everything was fine.
Probably a different problem but since this is one of the first results in Google when trying to find a solution I thought I would mention it here for future reference. Hope that’s ok.