Aha, I think I may have it, do you have special characters or spaces in the ROM name? I renamed all mine to simple short words while testing. Try renaming yours to just alphanumeric characters. I'll have a fiddle with PyBoy to see where the problem is.

[Edit] Heres a new version, I've fixed up PyBoy to deal with filenames with spaces, also got rid of that annoying crash when you try and select a different file. Here it is:
http://chaoticbob.nfshost.com/maemo/...14-1_armel.deb[/edit]