I have a problem with my M1530. When I turn it on the blue lights on the bar adjacent to the on/off switch flash but it doesn't do anything else. No Dell splash screen. It just sits there and does nothing. If I switch it and off between 6 and 10 times it eventually works.

I read somewhere that it could be the HDD failing so I have replaced it and for a couple of days it was OK but the fault is now reoccurring. 

Any ideas what it could be?