There is a nasty new virus/trojan on the loose that can easily infect the newest versions of Internet Explorer and Mozilla Firefox. The current version of Firefox (18.104.22.168) is easily infected with these exploits and it happens automatically in the background, you won’t even recognize that you’re being attacked without a good software firewall in place to protect your computer.
The exploits are being hosted in popular websites that are linked to sites such as DIGG, Myspace, etc. and thus far a lot of people seem to have been infected. If you think you have been infected please download and run Spybot Search & Destroy immediately as well as update your anti-virus software and do a full system scan. You should also do a full system search for the files xpre.exe, xrun.exe and poolsv.exe.
The next step if you’re still unsure is to take your computer to a PC repair professional such as those here at my PC Techs