Ok, so here's what happened.
No problems what-so-ever for weeks, formatted reasonably recently. Decided my fans were too noisy, so I shutdown, dabbed a little Vaseline inside the noisiest one, all happy. Boot back up, and it gets the the windows loading screen with the little bar going across. Hangs there for 3, 4 maybe 5 minutes, and then finally gets into Windows and runs fine.
No explanation is really given, Windows runs fine once it gets past that screen, and no other problems are evident (except the fans didn't get any quieter lol).
Any ideas as to why I'm getting this random hang would be appreciated.