This is more likely a software issue than anything to do with hardware.
Does the loading stop at the same spot each time?
How long after the black screen do you wait before you shut down and re-start? Leave it a little longer next time to see if it cures itself as it seems like a corrupt file.
Watch the flashing of the activity light on the front of your tower, does it stop about the same time as the black screen?

Next time this happens and you reboot take a look here once it is running
click Start
click Control panel
click Administrative tools
click Event viewer

Do not get frightened off by all the gibberish you see while doing the next bit Shaddy. Just quietly review it for clues so we can help you get this sorted out.

Now we have a new window with 2 sides, on the left side click on System.
Now look on the right side for red error messages, scrolling down if needed.
Double click on any of these to see what it says. You may not understand much of it but look for clues and any error message and error number. There is also a link underlined and in blue text, you can click on that the bring up a help page.

When you have finished there go back to the left side of the Event viewer window and click on Application and see what there is there regarding errors or warnings.

Shaddy you have started 2 threads and Zep has started helping you on the other thread so please ignore this thread and we can all work on the other one to avoid confusion

I will copy and paste my thoughts in the other thread so Zep and others with ideas can jump in there.