reboot the pc and press the f8 repeatedly untill you are presented with the startup options choose "safe mode"
after the os loads click start and type "msconfig" (without the quotes)
click on the startup tab and uncheck everything not from microsoft. you can tell by the manufacturer collum. click ok and then apply and restart.
when i start my laptop it start normally but after a few sec it appear a black scree.but the cursor moves.plz answer as quick as possible.its for my mom. thanks in advance
Do you mean that after you login and it shows Welcome, you are taken to a black screen with only the cursor visible? i've experienced that too and the only solution is to really reinstall Windows. The problem is most likely caused by corrupted system files.