Occasional Starting Windows hault

For the last week and a half, my computer has occasionally stopped at the black screen with the Windows Logo and the text "Starting Windows". I do a hard shutdown, and when I restart my computer, it gives me the option to Launch System Repair. I've tried this option once and it didn't do anything. I still get the problem, so to remedy the situation, I just do another hard restart and cross my fingers. Sometimes it'll stop, sometimes it will continue loading.

Unfortunately I don't have a System Restore option from the date/time before the problem started.

My computer is just over 4 years old.

Any ideas as to what's going on? Any suggested fixes?

I will offer this. I took my computer into the store earlier this year because of a startup issue, it wasn't reporting the temperatures. The technician found a bad memory slot and moved one of my RAM chips over, then disabled the message because even though the slot was bad, it didn't correct the error.

Could my motherboard be failing or is this a software issue? I honestly don't remember applying any updates during the time when this first happened, but I could be wrong.

Your machine is old enough to start experiencing failing hardware, especially if it's been heavily used.

Anyhow since you bring up a possible ram issue.
It may be the ram itself and not the slot that is bad, ...or it could be the slot
Running this overnight (5 to 7 passes) will detect bad memory for you. Though if it's as bad as it sounds I'm pretty sure you'll start getting errors almost right away if memory is the culprit. (it really should be run for half a dozen passes or so to be safe though)

edit: oops forgot the link http://www.sevenforums.com/tutorials/105647-ram-test-memtest86.html