Just started happening last week on my friend's laptop. It sticks on the loading screen for ages (like 5 minutes) then just goes black without ever showing the login screen.
It's running Windows 7 Home Premium 32bit. Works in safe mode and have done a virus scan using AVG and couldn't find anything. Done a memory check but that seems to be fine. Tried updating windows in safe mode but the Windows Update won't open.
Tried doing a system restore but it failed. Tried using sfc /scannow in safremode but that said there was nothing wrong. Tried disabling the graphics card but that didn't make a difference.
The computer didn't come with a windows cd so tried downloading "Windows 7 Home Premium x86 SP1 U (media refresh)" Windows 7 Direct Download Links
and then doing a Repair Install using the this guide Repair Install
but on step 9 it says "to upgrade you need to be running windows 7 with service pack 1 installed..."
Any help would be much appreciated.