HELP i need serious help...

I have just bought a PSP (don't know what model- probably 1000+) from eBay..It's a confirmed CFW..Based on the system software, it says 5.50 GEN-D (FULL)...

I have recently bought an UMD game, Dante's Inferno but I can't seem to play it..I kept on getting errors stating, "The Game Could Not Be Started. (80020148)"..

Is there any other alternatives for me to play this darn UMD game? If possible, I prefer not to update my CFW (afraid of messing it up as I am a total amateur in this PSP thing)..

Is there some sort of settings I need to do in order to play this game and not affect my other games if i were to change its settings..

Thanks in advance..