Ok i purchased crysis 2 from ebay. The seller said it was a brand new copy which is what i wanted, but on arrival the game was opened. so I was just curious if there was a possibility that they did install the game and their pc had a virus could it transfer to mine?
As long as it is a genuine retail disc and not a copied cdr/dvd-r disc, it will have no virus's on it as it is not possible to add any data to these types of disc -Bugs are another matter as most games have a bug or two but that is down to bad progamming and usually sorted via a patch from the games website.
the only thing you have to be wary of is that crysis attaches itself to the first account its registered to. so if it has been installed b4 and then you try to play it on a new machine, you wont be able to use the key as it will say key already in use.
you will have to talk to e.s. support. to either get a new key (they will charge for this) or get the key disconnected from the old account.