Originally Posted by
marzsyndrome
I should warn everyone to be aware when extracting this directly to their PSP (or even just copying it manually onto there) - you need to make sure the "Archive" flag isn't enabled for the directory, particularly if you store your roms in the same place as the emulator.
If it's enabled, then PicoDrive will assume that its own folder is an archive and report an Invalid Archive error if you try to look into it (the rom browser starts off outside of the directory and in the area where your other game folders are). I'm not too sure whether the flag is a problem with zipping it up in the first place, but it is very easy to not notice it until you attempt to use it. This problem has existed in all versions of the program to date.