So I bought a 4.0gb stick off of eBay (Sony), and synched it up. I was planning on using it to store more CSOs than my 2gb, which I was going to use for backup. I backed up the 2gb stick, and clicked to drag it over to the 4gb. After it said all the files where on there, I checked it using PSP Content Manager, and it said "Invalid ISO" instead of showing me the .png for the CSO. I figured, eh, the program's fault, so I tried wiping it clean and starting over. Now half of the CSOs work, half don't. And now my EBoots in the 1.5 folder are all corrupt, when I know they work fine (same with the CSOs). So I've troubleshooted like fifteen different ways, and I was going to see if anyone can help me. I figure maybe it's:
1)The card's problem. It's cheap, and off of eBay, maybe its some faulty memory- the trick is, it stores 4gb and it works occasionally, so I know it has the capacity, or at least the capacity to work.
2) Some problem between my External where the CSOs are and the PSP holding the card. Maybe the data is getting scrambled somewhere or something
3) This is the least plausible, but my friend thought he read something on Rapidshare or Megaupload or one of those sites about self terminating files. I've never heard of this, and these files work occasionally and on other PSPs, so I really really doubt this one.
I was running 3.10 Oea', but I upgraded to 3.40 Oea hoping to fix the problem. CSOs seem to work if I format the memory card, synch it up and then click drag one or two over really fast. Example- I can fit like 5 small CSOs (Bomberman, Puzzlequest,etc.) or like two bigger ones (Valkyrie Profile, GTAVCS), but then everything quits working after I drag that over. Same goes for the 1.5 eBoots. They'll work at first, but then I can't drag any more over because the card labels everything invalid. This is driving me insane, because its so inconsistent. My backup plan to just run a DebHook seemed to work for a sec, but that just seems to troublesome sometimes. Any and all help will be appreciated!
I've tried moving CSOs back and forth between my 2gb, and last time I tried it worked, but I'm worried that the problem may spread, so I want to leave what works on my 2gb as untouched as possible.
Thanks again!

well the problem could be the memory card, if its off of ebay theres a good chance its fake, and i couldnt really understand but youre saying that the computer like stops transfering files in the middle of transferring? if thats it then just restart your computer

To me it just sounds like a bad mem stick if they worked fine on your 2gb. I wouldnt worry about the 2 gig stick but just seems like you got a knock off that really isnt up to par.

It transfers, but it seems like the data is scrambled after it transfers. Sometimes it will transfer and say it is invalid the first time, but I will delete the CSO and retransfer and it will work. It's really finicky. My 2gb did this for a bit a while back, but it seemed to work again quickly. The 4gb is still being stubborn. If its bad memory, A) is there any way I can format it into working, or correct bad sectors or something and If at least some of it works, wouldn't that mean that there's at least some valid good memory? It seems like all of it can be used, there's just something wrong on either the PSP end or the PC end.

well like we said, the memory stick is most likely fake, theres no way to fix it so it would work. next time buy a memory stick off of amazon or sandisk so u know its real

Try re-transferring them, that's what happened to mine, but now its fixed

If the isos worked on the 2gb mem and did not work on the 4gb then you probably have yourself a fake memory card of ebay .