[MrForbes]

If you really can't be bothered to check all the connections...you probably should not have asked for help????....

Seriously, just because you don't think this is the problem, until you actually check the connections (really check them), you won't know if they are OK or not. You have described symptoms which are commonly caused by poor power distribution connections, so it would be time well spent seeing if that is the cause, even if you have never experienced this situation before--others have, and several folks here zeroed in on this as the most likely culprit.