Never had this happen before. Entered Riften and Durak attacked me.

I reloaded and checked to see if I'd been infected by a vampire and I hadn't. Entered again and same deal.

The only thing I can think could have happened is that something went wrong when I had to kill Tyranus in Markarth. That was a long time ago.

Any thoughts?

Have you got a bounty in the Rift ?

No bounty. The guards just scattered when he attacked

Haven't started the MQ so no chance I hit him by mistake while fighting a dragon or anything like that.

I tried drawing then sheathing my weapon but that didn't work.