If your AV keeps being disabled then it's almost certainly a virus. You could do a clean but you may not get rid of all the nasty stuff. I would recommend backing up all your data to USB stick or another partition then do a format and fresh install.

Poser 11 , 180Gb in 8 Runtimes, PaintShop Pro 9
Windows 7 64 bit, Avast AV, Comodo Firewall
Intel Q9550 Quad Core cpu,  16Gb RAM, 250Gb + 250Gb +160Gb HD, GeForce GTX 1060