hi, can you tell me if you are able to get in to BIOS? You have to press one of the F keys (possibly F2) or even the enter or DEL key, up and down as you boot. If you can, is the hard disk recognised? Can you still boot, if so can you boot in to safe mode? If so have a look in event viewer for errors. This can be caused by hard drive problems, even memory problems. Have you backed up all important documents? If you go to the web site of the hard drive manufacturer, you can download their diagnostic program and burn it to disk (a .iso file), boot with it and test the hard drive. Also you could download memtest, burn to disk and run that on the memory.