There's no point in trying to use a Windows antivirus program to solve what sounds like a Linux driver problem. Windows viruses don't work under Linux, though the rather rarer Linux viruses do. They are rarer because the vast majority of machines are Windows and reciprocally don't run Linux viruses.

Locking up sounds like some driver problem. The drivers most intensively used are the HDD i/o system and the video driver, so they are the prime suspects. Googling 'Ubuntu locks up' gives quite a lot of hits, including this, that suggests disabling some of the more advanced video features.

Noting exactly when it locks up could give some clues- e.g. network driver or some other, but these like the HDD tend to be a lot more standard and so better debugged.

Linux ought to have swept proprietary OS's away by now, if it weren't for its own supporters, whose first response to any problem or shortcoming is often to deny that it exists, then impugn the intelligence of the reporter, next to blame the hardware, and finally to recommend a switch to another flavour of Linux. They do have a big problem in that the manufacturers of chips are often reluctant to reveal details that would allow a proper design of a driver, but the real problem is the fragmentation of effort and lack of a desire for intercompatibility. I often think that much of the effort must be by paid agents of the dark Empire, they are so effective at preventing the technically best OS available from flourishing.