hi,
Some antivirus may flag cracks as viruses because of the nature of the cracks. Some of these cracks contain similar codes to to what real viruses do and some do really contains virus as a way to get unsuspecting users to run it inform of luring you with a crack.

Now if you used cracked AV, don't go complaining that your AV did not protect you from this or that because the crack may have alter some stuff which the program manufacturer cannot guarantee against.

In fact got get a real copy. They don't cost too much nowadays.

p/s: we don't need Kaspersky spam posters telling us how cheap they are or how effective they are...