This must be a behind the scenes agreement among antivirus vendors that they start to act as moral police.
I just got a message from Norton Internet Security 2009 software that after scanning at least 3 year old zip archives on a temporarily connected usb disk it deleted the tnt-acdsee.v3.0.b1209_crk.exe file being "trojan". Similarly a keygen.exe was deleted which belonged to an ancient game software. Furthermore one DOS joke program (mirror.exe, mirroring each character on the screen) was deleted too.
My advice: if you are fond of older cracked versions, do not store them on hard disk, use only CD/DVD for archiving, because the antivirus software deletes them without asking any question. During installation of such cracked version (from your archive CD) disable temporarily your antivirus software.
I don't like this type of evolution at all. I pay for the antivirus function (including all other stuff potentially harmful for me) and not for the antipiracy, anticracking, antikeygen etc. I believed that Norton is on my side and is not acting as a selfmade police watching the interests of the multimillion software lobby. To hunt keygen for ACDSEE v. 3 is ridiculous when the actual version is 9 at the moment. The software gigants has no understanding that there is a type of user who prefers the well-known simple interface and refuses to enter this crazy spinning upgrade caroussel. I do not see that such old cracked versions are doing economic loss for the software business, it is more a moral question.
We started to hate Microsoft because the frequent patching was more and more used to promote MS, to f.ck up rivals software, hunt down pirate copies, to collect information on users behaviour etc, shortly a lot of things we not payed for, and strongly dislike.
The antivirus software branch now made a point and acting moral police. This wouldn't be a serious problem if the message you are getting would be truthful saying e.g. "Erasing keygen.exe, a software creating illegally user keys". Instead we get a lie claiming that the ancient keygen is a trojan (a malicious software masquerading a useful function).
The only sympathetic gigant Google still resist the temptation to play the role of the eager moral police.

A search after keygen still results 75 million hits. I don't mind at all that a search after "child pornography" do not lead to such pictures, but rather to discussions about it. I suppose there is a delicate manipulation of the search engine, but not too much yet. The temptation must be enormous, things you don't find with Google does not exist for people in general.
It needs a delicate touch to know where the fine borderline is. Google with te motto "don't be evil"
http://en.wikipedia.org/wiki/Don%27t_be_evil did not get caught yet (hm, there was something in China though) but Norton and probably the other antivirus companies too lost my sympathy
Don't get me wrong. I am a honest guy, when a police chases a robber I am on the police side. But software piracy is not that threat what the lobby tries to show us. The frequent new versions, the radical platform changes (16 to 32, than to 64 bits) are marginalizing the economic loss. If somebody, who can not afford to buy a legal license of let's say Microsoft Word do install an illegal copy, does very little harm to the giant, in fact by learning the functionality, getting used to the interface, the features motivates a license buy later on. The same philosophy is behind the cheap student licenses hoping that the student will advocate for the well-known software later privately and at the job.
Summa summarum: the antivirus software should do what it supposed to do and not playing police.
Laha