At some point in my browsing anti virus scan demo was installed in three places:
Registry
Internet Explorer temp file
Windows 32 directory
If you are not familiar with anti virus programs like McAfee you will believe the various pop-up screens claiming you're infected with either a virus or trojan. You eventually find that every application you attempt to start quits claiming to be infected.
Even your browser will fail to connect to various websites claiming to be infected. Gradually you won't be able to do any productive work with your PC. At which point you'll start getting full screens asking to scan remove viruses from your system. Just $49 on your credit card. According to the Internet there is not virus just a money scam.
Now all this is a scam. What you have is malware blocking your applications and system software. I did a full scan but Mcafee was locked out. Fortunately I a copy on my flash drive of "malwarebytes anti-malware."
I restarted my system and booted it from Safe Mode using PF8 key to get into safe mode. Selected network and safe mode. This the minimum number of system components and applications. The scam anti virus demo scan isn't even running.
Install anti-malware software and run it. I chose the free version 1.5.1 which did the job in about 18 minutes and 88,000 read files. Only three files infected. A simple mouse click on remove got rid of them. I had to restart to complete the process. Normal boot selection not safe mod. Turn off proxy use by my browser and I was set to go with a faster system with no pesky fraudulent anti-virus messages popping up..
All in all not too bad a recovery. This is the first one I've had in six years. We are in a game of spy versus counter-spy. Find a weakness then it gets patched. Again and again this process evolves. From real infections to perceived infections for money. Whether you buy commercial or use free anti-virus software please get either. Also get some malware checkers and Super anti-spyware checker. They should give a stable system until a major evolution occurs.
So don't give up and keep downloading the updates to those products. Cheap insurance to formatting and re-installing your system and applications plus data. You do have the system files and boot sectors right? Have you made any recovery disk yet? USB drives are bootable this days.