sttminus not found?

Heya, I finally got Doom2.wad to work on my psp, but when i try to play Doom.wad the game starts then when i choose the difficulty the game freezes and on the top of the screen it says "sttminus not found". I read on other sites that when it says "sttminus not found" its an older version of doom that u need to update or something but they didnt say how to fix it. Anyone ever get this? Could someone help me out if u know how to fix this problem?
thx alot =D!

Nvm i fixed it =P

Hi, i've got exactly the same problem as you, please could you help me? How did you fixed it? and... can you save games in doom2? i can't.

thanks!!

i;ve been able to save games in doom2 but not in ultimate doom

i fixed it installing doom-psp 0.05 plus, now i can save games and use cheats, but i can't run doom1 yet. I have the same problem as TimeJack, "sttminus not found".