Thanks for the reply. It doesn't disconnect right away though since it takes a minute or so to completely disconnect from the net, but it does this when entering Ygopro (I'm not sure on if you already have Ygopro up, but I'm pretty sure I would have tried that too).
Anyway the Ygopro version I'm using is 1.033.3 V2, and the computer is a Windows Vista (not entirely sure of too much else, but I'll answer what I can)
Also, I just tried extracting each element of the update separately on the previous version, and the file "cards.cdb" was the one that once again caused the issue after extracting the pics and script folders successfully. But messing around with a cdb file without knowledge of it would be just as bad, so I hit a brick wall here.