SBAC: Your BSODs could be Comodo, that's definitely something I'd check early on, but do seem potentially hardware-related. Run a memory scan (Memtest86+ is my recommendation). Also, did you actually move/change any hardware *inside* the case recently? If so you might have bumped something...
You could try some "quick and dirty" elimination rounds to save time with Memtest86+ since the in-depth scans take a while to run.
Try pulling out half your RAM and the see if you're running into the same problems. If so, replace those with the other half and see if the problem goes away. If that's the case, a suspect bad stick is in the first group. Then try alternate loading the sticks in the suspect group one at a time until you get your error.
Once you've identified the "most likely bad" stick, pull all the other memory out, install the bad one and run Memtest to confirm it's the culprit. It takes a lot less time to test one RAM stick than it would all four if you're reasonably sure you've identified the bad guy.
If the suspect stick passes Memtest's scan (or if you get the same errors no matter which RAM sticks are installed) then there's a chance there's a mobo or memory slot hardware issue. You can do a similar process of elimination round on the slots to see if one of those is giving you hassles. If it doesn't matter which slots are used, or what RAM is installed, then there's a good chance it's a board issue. If updated motherboard firmware and drivers don't fix the problem (you already checked for those, right?) you may have a flaky mobo. Bummer if so... Check and see if there's been a recall or announcement at the mfg's site. You may be able to get a free replacement if so.
Note: Due to the low-level integration of video, a spooky video card can also cause a huge number of weird problems that don't seem related to video. So I'd also suggest you run your manufacturer's video board diagnostic (if they offer one) before deciding your mobo is shot.
I recently donated a nice PC somebody gave me last summer to a non-profit. It was throwing BSODs every hour or two. The owners decided to toss it and buy a new one because a big store service department ("after extensive testing" $$) told them the motherboard was shot. It wasn't. Once the bum vid card got replaced it worked like a dream.