As a last resort try this :
In normal mode, run an online antivirus check from at least two and preferably three of the following sitesBitDefenderComputer Associates Online Virus ScanPanda's ActiveScanTrend Micro HousecallWindows Live Safety Center Free Online ScanThis scanner from Trend does not require an Active X to run.
1. Detects and removes malware ( viruses, worms, trojans, etc. )
2. Detects and removes grayware and spyware
3. Restores damage caused by malware to your system.
4. Notifies about vulnerabilities in installed programs and connected network services.
5. Multi-platform support for: Windows, Linux, Solaris.
6. Easy-to-use with the Microsoft Internet Explorer and Mozilla Firefox.
I would suggest to run the Windows Live safety centre test and Bitdefender test to see what is going on. Formatting is absolutely the last step because it is such a PITA