Well... I have an intel pentium 4 at 2,4 Ghz - 512 ram - asus motherboard pep4 and suddently when I opened my PC once after the windows logo I get a black screen and my mouse pointer! That's it ! I cannot do anything further nothing works even if I log in safe mode. Tried also to repair my windows installation booting from the cd but no luck!! Any sugestions?? Thanks in advance! :)

Have you tried, on the screen that gives you option to open in safe mode to choose the option to Start with Last Known good configuration?

What happened when you tried a repair?