which firmware are you tring to go to? 3.40 oe-a or 3.51 m33? You might want to reformat your memory stick and start from scratch cause when theres other stuff on your memory stick it sometimes interferes with the update/downgrade process.
If you want you can use the winstallers from here and it will load all the stuff on your psp for you so all you have to do is click update from your game > memory stick.
WTF is MSS? Sorry man but I don't know if I would trust a man that didn't know his own firmware claiming all the bugs are gone. And if they already have 7 patches I'm sure there will be more. But w/e, I still see no reason to upgrade from 3.40OE-A.
It's not the religion that causes wars, it's the men who use religion as a means to control people that do. They call me tater salad.