Malware may reinstall itself multiple times if you don't delete its core files. This may require tracking down dozens of files in different locations.
We recommend downloading Advanced System Repair to eradicate Malware for you (it should cut down the time to about 15 minutes).
No matter how vague your error messages are, at least they tell you something about the problem. Since there is no error message when your computer simply fails to start up, the user is often left scratching his head. There are many reasons why your computer may not start up; here are some of the most common solutions.
System restore: With some problems, like viruses or operating system errors, you may be able to fix the problem using a system restore point – even if your PC isn’t starting up. Depending on the model and manufacturer of your computer, it should come with a special system restore disk. Place that disk in the drive during start-up in order to access the system restore screen.
If you don’t have your system restore disk, then most PCs have a special button you can press at startup to access the menu. For example, many Dell laptops use the Ctrl+F11 keys. While you’re at this stage, you may also want to consider repairing your Windows operating system using ‘Startup Repair’ (in Windows 7 and Vista) or ‘Repair Installation’ (in Windows XP).
Device error: Sometimes, a startup error will be the result of a new device or driver that you have recently installed. To make sure this isn’t the case, disconnect all unnecessary devices from your computer, and then try to start it up. At the very least, this will show you what isn’t causing the problem, which will help you down the road.
Power supply failure: Some PCs will start up, get past the BIOS screen, begin to load the operating system, and then suddenly shut down. If this is the case, then you may have a power supply issue. In the beginning stages of startup, your computer is not drawing on all its resources. Then, when the operating system starts up, it needs to rapidly access the hard drive, which could push an older power supply over the edge. Replacing a power supply isn’t as difficult as you may think, and you can usually get a decent replacement for under $100. Also keep in mind that sudden shut-down at any stage of the boot-up operation could indicate a power failure.
Safe Mode: Press F8 as Windows first begins to boot to enter safe mode. This will disable all sorts of functions that commonly cause problems for your PC. Sometimes, you won’t even need to fix anything after starting in safe mode: a simple reboot into the normal mode of Windows should clear the problem up. In safe mode, you can also use system restore to undo any recent changes you may have made.