I have tried everything and follow exactly the intruction, but I still got the error message "SH-1 invalid". Anyone know how to fix it? This is what I do: 1.I format my memory stick. 2.I copy the oeupdmaker and oeupdmaker% file in my \PSP\GAME 3.I copy 340.PBP and 150.PBP (rename them as 340 and 150) in PSP\GAME\OEUPDMAKER folder.(I have 3400MB room for this) 4.Then I execute the program. It run well at the begining, but when it come to almost the end, the error message show as I mentioned about, then automatically switch back to normal screen. I currently just downgraded from 3.03 to 1.50. Please give me some advice...thanks!