Sorry to hear that! I'm always worried something like that would happen, and wouldn't have the strength to restart... Skyrim would be over for me... any idea why they stopped loading? Did you have a lot of mods installed?
I got too frustrated with the extent of the problem to unemotionally investigate it properly.

I never use downloaded mods, and hadn't gotten to the point where I mess with the game myself, so it wasn't that.
My investigation led to having gone to Dead Men's Respite early in the game and picking up the Verse and meeting the ghost. Because I explore a lot I also had all of the found Bard's College items long before I joined. When I joined, The Blue Palace cell would not load, then Dead Men's Respite would not load, then the other cells in the game associated with quest items I had picked up.
The game has been patched in regard to these items since then, and the issue is probably fixed.
My second play through I just avoided all of those cells until I had joined the Bard's College, and everything was fine. I do not know for sure what caused the problem, which made me superstitious, but my game works fine now.

One other problem I have had in both games is after completing the Companions questline Farkas wants to go kill his first dragon, and in both games he takes us to Autumnwatch where there is no dragon. In my second game when this happened I just reverted to an older save and have avoided speaking to Farkas.

Starting again turned out to be a lot of fun, since I played the DB and TG questlines I hadn't yet done, then decided to become 'good' and re-played all the questlines I'd already done. Enough time has passed to make it interesting to play through again.