|Difficult to say but it could be some sort of loose connection inside. The other possibility is edge connector trouble. You could try using a pencil eraser on the RAM edge connectors then popping the sticks in and out a few times (to clear any oxide off the sockets too) before pressing them finally home. If your graphics card is separate do the same with that. Edge connector issues are not at all uncommon, especially if anything inside has been even slightly disturbed.|
The above was assuming the iTunes trouble is part of the same issue - could be.
There's a vague possibility of this being malware. We can suggest a quick check if necessary but for now I'd leave that idea on the back burner.
Always pop back and let us know the outcome - thanks