I need some help in removing a virus. Some time ago I must have caught some nasty malware. At first computer just switched off, after restart Windows couldn't load, startup repair and system recovery also didn't fix it. I had to do 'Dell Factory Image Restore' to load Windows, but even then there were still few problems. Most of Windows updates failed, after installing an update and restarting the system Windows couldn't load and startup repair brought system to the point before an update. That happened to most of updates, I managed to install just a few. When browser was running many unwanted websites were opening by itself, also sometimes system crushed and restarted after awakening from sleeping mode. I scanned system with DR. Web Cureit, one item was foun - "Master Boot Record HDD1 infected".
I wanted to cure it and after restart Windows didn't load. Again neither startup repair nor system restore could handle that and I had to do 'Image restore'. When hard drive was formatted and System image installed, after restart Windows again can't be loaded (computer restarts, startup repair can't fix it).
Any ideas how to handle this? I would be very grateful.
PS. Totally forgot, I'm using Windows 7 64-bit.