With my my first character, dungeons respawned. I must have cleared out Valtheim a dozen times with him. The ones after though though, had different luck. Months in game would go by, and dungeons would still be deserted.

It is the 21st of last seed, and I just cleared out the bandits int he little cove beside Whiterun, and I am on my way to clear out Halted Stream Camp with my new guy. When can I expect those places to be filled with enemies again to see if there is a problem or not?

Cleared dungeons = 30 Game Days

Not-Cleared Dungeons = 10 Game Days

Some Dungeons are marked as non-respawning, however: http://www.uesp.net/wiki/Category:Skyrim-Places-Safe

Ok, there is definitely something wrong then. Has anyone heard of this happening to anyone else?

The bandits in valtheim towers(and some other places) not respawning is a problem im familiar with. I think it was a bug in the 1.5 patch that should have been fixed with 1.6. Allthough with my nord character their is stil no bandits coming back there.

The bandits in Valtheim Towers and Halted Stream Camp are supposed to respawn if you stay out of the area for 30 days or more. There was a known problem with non-respawning enemies but it was fixed with 1.6 update. At least I thought it was fixed.

I have 1.6, and I am telling you, the land is DESERTED when I walk around with my level 47 Nord. I started a new character, so I will see how it goes in 30 in game days.