Error Msg when loading rom: "Failiure to Allocate Memory"

Hey guys

Im having trouble with P64 when loading roms, whatever rom I load I get the error in the title. Any ideas?

Im running Windows XP, Intel Celeron 1.50 ghz, 446 MB ram, ATI RADEON XPRESS graphics.

My roms run fine with the Mupen emulator, so im not sure!!!

Thanks