if your stuck in Russia on the level with armor guys here is a tip: upgrade infection chance past 100%
The armor makes them slightly less vulnerable. Oh, and the tank doesn't infect anyone.
...or a zombie could've bitten his head off, or maybe aliens really did abduct him...or at least a hobo stole his computer or somethin'...don't know where he'd get the electricity but oh well.
I think it's not working because of D...the creator of the game decided to have a little fun wit u guys by purposely knockin the game off track, thereby making you post about aliens...