I have a psp with update 2.06, and I download tons of crap on to it! Movies, music, pictures, but there is a way to get rid of viruses. Hook it up through a usb cord, and re-upload all the root folders with everything the system needs to run. Its just like reinstalling windows, only a lot faster, so if I were you, I would save all your PSPs folders on your pc.
P.S. I have had to do this before, because my psp was crashing and I had to add all my time, and date crap over again, but I "reinstalled" the psp os, and everything worked fine again. And by the way, put all your saved data on your pc aswell.