When I turn on my PC it sometimes freezes before it reaches the BIOS screen - with only a cursor flashing against a black screen. The only way I can get around this is to switch off and power up again and this usually works. My operating system is Windows 98se.
Has it always done this or is it a recent development? If recent it might be down to a piece of software you have installed or something trying to load during boot up. Try booting your computer and going to run and type misconfig and uncheck everything that is booting up at start up except the necessary items, reboot and if it boots ok then it must be down to one of the items trying to load. If this is the case unfortunately you will have to re check everything in turn to find the culprit.