Hi,
Try pressing Ctrl+Alt+Del and see if you can access "Task Manager".
If not, put your windows CD in the drive, set your boot to CD and see if you can start a repair from CD, if you can we will guide you later what to do.

It could be faulty ram or ram not specific to your PC. Ram have different mhz. DDR400 is backward compatible so if you require DDR 333mhz, you can use DDR400 but you cannot use dDDR333 with DDR266 mixed.

If you are using AMD and a Nvidia video card you need ATI video card. There have been some compatibility erros when using Nvidia with AMD.

roll back your drivers recently installed in your pc

the computer will not boot ,please explaint to poster how to roll back drivers if they cant boot computer

Just a thought, you might have added a component recently and it is this item that is causing the problem. Maybe you have a USB device connected at start up? Maybe you have something in the startup processes?

You might have to do a reinstall, just upgrade, and not new install, if the problem continues. It is hard to determine a problem without all the facts about what you may have done or not have done. Maybe there is a CD in the CD drive?

If you have set your CD drive as master and your HDD as slave, this could cause a problem especially if there is a cd (DVD) in the drive.

You might have inserted a new Video card or changed the Ram or something.

Also, some mouses can cause this error if the mouse has side buttons as well as regular buttons.

Also, if your keyboard has internet buttons and all those extra option keys, you may have bumped a key on start up or the keyboard might be faulty. Igf the keyboard is wireless, then new batteries might be needed.