Well I'm going to keep this short before it crashes, but Firefox keeps crashing on my PC. Once I go on this site and almost log in it immediately crashes. I was playing the RS client if that has anything to do with it.
Also, sometimes some index of pages randomly opens with some foreign language in the address bar.
Also, sometimes some index of pages randomly opens with some foreign language in the address bar.
That makes me believe you have been infected. Have you been browsing them 18+ sites you shouldn't be browsing? ;p
But back to the problem what does your crash logs show? Does it usually crash when you are using a certain feature like Flash? Check the crash reporter and see if that can help you narrow down your search as to what is wrong. Firefox usually keeps two locations for the crash reports (One for those that have been sent to the firefox server already and one for those that haven't been sent yet).
On windows you can find them at (use the CMD or just navigate there)
%APPDATA%\Mozilla\Firefox\Crash Reports\
Mac OS
/Users/<username>/Library/Application Support/Firefox/Crash Reports/
Linux
/home/<username>/.mozilla/firefox/Crash Reports/
This link should help you open and view your reports also http://kb.mozillazine.org/Mozilla_Crash_Reporter
In addition to what Zereo has to say you could also open Firefox to a blank page and go to Tools->Add-Ons and disable all of your add-ons and extensions. Then come back to this site and see if it crashes again.
The pop-ups suggest an infection but it may not necessarily be Firefox that is infected. If you switch your default web browser to another client and the pop-ups open in that client instead of Firefox then you can assume that the infection is separate from the browser. If they still open in Firefox then it is probably a malicious add-on.
What OS are you running? Do you know how to give us a dump of your running processes?
I'm running windows XP. It isn't popups, just opens up a new window. Now that I've restarted it doesn't happen as much. I installed google chrome though, so hopefully this shouldn't be a problem.
I would still investigate it because it sounds like a infection and the last thing you want to do is just ignore it because it isn't happening as much.
That is what most users believe until their computers are useless and they need to do a complete fresh install. AV's aren't the ultimate protectors of computers many things get past AV's without much sweat.
I think I accidentally set something as a hotkey
A hotkey wouldn't open up a new tab or window in a weird language. But then again it is your choice to investigate it or not, just my advice is be proactive not reactive.
That's infected....you need to restore your pc..reinstall windows xp or other os like ubuntu....I am using ubuntu and the best thing is there is no virus.....and some virus are stealthy ...like for example...your virus could have changed the Firefox code...and set it to some other thing...your avg would know that
At your point yes. If you want to try fixing it you need to determine exactly what is wrong by narrowing everything down.
You can start by doing what ComputerGeek said and also checking your FireFox logs. That should give you a idea of why it was crashing and doing what it was. It might just be some random errors and has nothing to do with a infection.
If his computer has, in fact, been infected by a virus there's no telling what other damage has been done to the system. Better to back up any critical data then nuke the system from orbit and start over.