No, I'm not a werewolf. Never touched the Companions questline.

Sometime after installing Dawnguard, I noticed I was no longer getting resting bonuses to xp.

No diseases, no active effects that would make that happen.

Is this a known bug? Just a display error?

Are you using the Lover Stone?

Edit: Sorry, Just saw that you mentioned Active Effects.

Actually yeah, I am using the Lover Stone - but only because I lost that xp bonus for resting! So that can't be it.

Are you really not a werewolf? I mean, c'mon, if I was a werewolf, I totally wouldn't tell you. I'd be like, "No, no, I'm not a werewolf..." and then, like, totally attack you, or, maybe be like,"Yeah, I have a friend, and they're a werewolf..." and you totally wouldn't know that I was secretly talking about me the whole time.

So, good luck there, "Mr. I'm-not-a-werewolf." We'll see.

Ok. So you lost the Well Rested bonus BEFORE getting the Lover Stone? Then I have no idea what's wrong. It's never happend to me.

Just in case you don't know (Im pretty Sure you do) you can't get the Well Rested Bonus while having the Lover Stone.