This sort of thing does happen but I've never known it to happen like this...the only way you can prove your innocence is to prove that the computer had a virus on it that did what you say...if it's any consellation when I got a pop-up once that wouldn't pop-off for an antivirus programn I kept getting a pornography advert alongside it that wouldn't let up...the two must be related...I use malwarebyte's anti-malware to get the virus off my computer...Maybe if you got one of those logs of from scanning the computer with an antivirus then you can prove your innocence...I hope you can because it sounds like an awful thing to happen to someone...
Another thing could you possibly look into why the admin guy(Ithink you said) would set you up to get fired?...I mean if he's very knowledgeable about computers he could of actually put the virus on the hard drive or software e.t.c...in the first place.
a month ago I got fired for useing the computer at work to cruise for porn, really bad places I would never go . I came in for work to take the inmates I work with to a meeting,I"m a counselor. I found all they're fourloughs not in the system , the DOC system, which is diferant than mine. so I rushed to get that done in another office. two days later I was doing genuine research on my computer and a virus came up trying to sell a anti virus, it put a homosexual porn icon on my desktop. it was a closed system and my suporvisor told me that there was a firewall, anyway. week later they called me in and said that corporate wanted to talk to me they read a statement, I said I denied it. they fired me.
I am totally innocent, the whole thing makes no sense, I was only there for an hour and a half. but they have me 30 min before I left to take the inmates. I have never seen a computer that got a virus two days later, also the evil administrator guy said that he mistakenly left my firewall down because he had emailed a bunch of stuff and for got to put it back up. suspicious, he screwed up I got fired, I know I was set up, if anyone can help I would apreciate it, any ideas?