Yes, it's a multi-question! But they might be connected.
Running Windows 7 Pro SP1 (32 bit). I tried running Combofix numerous times, with anti-virus installed and uninstalled. It freezes the whole computer right after it says it will start to scan, which usually takes ten minutes. It never gets to the part where it shows the stages.
I decided to try it in Safe Mode, and to my surprise Safe Mode starts in low res (640 x 480). I cannot change it in properties. Very weird.
My motherboard (Gigabyte ga-970a-ud3) doesn't come with a graphic chip, so I have an Nvidia GeForce GT 520.
This all started a couple of days ago, when MBAM gave hourly notices about blocking avast from accessing a website. After uninstalling, it's apparent that it's Firefox, not Avast, that's doing that. Might just be a banner ad that I can't find, but I thought a full scan was in order. MBAM and Avast! scans come up with nothing, as does TDSSKiller. I thought Combofix might be a good idea.
As often happens, that led to the Combofix freeze and then the Safe Mode weirdness. Any thoughts on the subject would be appreciated.