Symptoms are...
1. When I turn on the computer regularly and log in, I receive a message saying "The computer has detected a critical error. You will be shut down in one minute. Please save all your work." or something in that similar fashion. Strange thing is when I log in with Safe Mode and then log in normally RIGHT after logging off from Safe Mode, it works. It's annoying I have to repeat that process just to access my PC.
2. Mozilla Firefox and Internet Explorer don't start up. When I try to open either one of those browsers, I get a message saying that "Firefox has stopped working" or "Internet Explorer has stopped working" and it automatically closes. Maybe it's a security precaution that my PC takes, because the browsers are corrupted or whatever, but it bugs me. I can still use my other browsers (Google Chrome, Opera, Safari), but I liked Mozilla Firefox. It used to work, so obviously, the virus messed with it.
3. Anti-virus programs do not function properly. Installing the scanners are not the problem; the issue is when I try to scan. It scans right for several seconds and when it reaches a critical place to scan (System32 files or something like that), the application closes down without warning. Trying to open up the program results in another message informing me I cannot open it due to either permission or connection problems. Funny thing is when I copied the folder where the program is, I can re-do the scan. My mystery "virus" obviously tweaked something regarding the anti-virus service, but what?
4. My PC has reduced performance. Weirdly enough, going on Task Manager shows that I'm using 1GB out of 2 available GB of RAM. I have 3 GB of RAM total, but the little performance bar says I'm using half of my RAM at 1 GB... Terrible math? I doubt it. Also, booting up my computer takes longer and everything just doesn't seem exactly right and properly working like it was before the virus came.
What I've tried...
1. Re-installing the browsers that fail to open and the anti-virus programs do not help at all. They still fail anyways, after I try to start them up and I've downloaded many alternative scanners, but they fail.
2. Searching for the changes in registry and system files seem like it takes too long. Dumb approach, but I'm at my last rope. I've tried to fix the problem for several hours already (4-5 hours, at most).
3. I really don't want to re-install my operating system so please don't suggest I do that, unless you really can't think of any sort of solution to this virus that infects my computer...
Notes...
1. The virus doesn't seem to be spreading and causing more damage, as I see. Not sure though.
2. No pop-ups and other browsers work completely fine without random advertisements.
3. No suggestions that come up asking me to download other fake anti-virus programs to scam me.
4. None of my anti-virus scanners had the chance to identify the type of virus. Maybe Trojan?
5. I'm not good with computers, so explain everything step-by-step and thoroughly, if you can.
PLEASE HELP ME! I'll be really grateful, since I suck when it comes to computer engineering or debugging or whatever it is. This has really bugged me and nothing seems to work... so good luck!


EDIT: Please don't say I was dumb to go on insecure websites. I know I'm an idiot and I've learned my lesson, although I'm usually pretty safe while surfing the web... Loopholes in my firewall apparently.