Trouble loading welcome screen!

I have a Dell Inspiron 1521. Lately, I've been having trouble getting the welcome screen to load. When I turn my laptop on, the first Dell screen loads, then the little loading bar on the bottom of the screen. After that, the screen stays black. Sometimes the backlight stays on too, and the power light and wifi light stay lit. I've attempted several repairs and had to do 2 system restores. The computer loads fine for the repairs and such. I'm just sick of taking an hour of messing with it to finally get it working every time I turn it on. I don't know if this is a motherboard thing - from what I read on the other posts, it sounds like when the computer gets too hot it can fry the motherboard - because my computer has been getting extremely hot. Any help would be appreciated!!