Stop fast-traveling to locations like towns and stables, especially if it means you'll arrive at night. You're triggering the Vampire Attacks that come with the Dawnguard DLC.

Like the posters above have mentioned, it seems you've been triggering the Vampire attacks which are part of the Dawnguard DLC.

It sounds like you have the Dragonborn expansion installed as well, which would explain the cultist encounters.

Vampire attacks are unavoidable in the wilderness, but to prevent them from happening in the towns and major cities you must NOT fast travel, especially at night as that's when the attacks occur.

Travel by foot, or use the wait feature to fast forward to the morning before entering a city. However, if you DO feel the need to fast travel to a City, the safest way to do it is to travel to a location near by and walk the rest of the way.

I've done the whole of the Dawnguard questline and have avoided attacks in towns and cities by playing this way.

and besides.. Who wants to fast travel anyway? You miss out on so much if you do!

I would also download http://www.nexusmods.com/skyrim/mods/28235/? to keep important civilians out of harm's way.

The similar http://www.nexusmods.com/skyrim/mods/23906/? does the same for dragon attacks.

Assuming the OP is on PC, of course.

It does seem odd to me that the death hounds were attacking the stable. I have seen vampries and their homies out there, but usually they bee-line for the Whiterun gate, ignoring everything on the way. I don't know if I'd call it a bug, though.

Attackers often do have a habit of "zoning in" on their targets, ignoring everything else for longer than you'd expect. Dragons are particularly annoying in this regard. I suspect that's intentional design. Also, Lydia does have a habit of ignoring enemies - not all the time, but often enough to be aggravating. I haven't noticed it as much with other followers.

I can think of two ways to try to fix your predicament, but they both require a save in Whiterun. The first option would be to fast travel to Riverwood, wait until daylight, then walk back. The second would be to let the hounds kill you (they'll eventually come for you once they've killed everything else), then reload the Whiterun save. That might clear out the random encounter altogether.

I've had vampires attack inside cities during the middle of the day when I waited outside a city until noon before entering, so waiting for sunlight near cities is not a fool proof solution. I've had better luck with your second suggestion of fast travelling to a near by location (but not a stable or anything too close, it needs to be at least a short distance away, like the western watchtower). Wait there for sunlight and then walk to town.

On PC a mod is the real solution, but Dawngard is really annoying on consoles.

yep, i only do PC.

Thanks for the advice. Good to know I"m not crazy at least...I think I'm not.

I will try those mods. ha..I did notice them on nexus but wondered what in the world you would need them for. Looks like I've found out.

(unfortunately, this mess caused me to accidentally save over a good save I had so I'm stuck with dead horse and vacant stable in Whiterun..unless I backtrack to a much older save). Note to self: save more often

Yep. That's the first rule of playing a TES game. Save often and keep your last dozen or so saves so you can revert back if you run into trouble.

Since you're on PC, I'd also highly suggest the Unofficial Patches and SkyUI.

Yeah, and iHUD and Less Intrusive HUD, unless you like the vanilla HUD, personally I cannot stand the vanilla HUD and it takes both of those mods to make it fully customizable, but they work together flawlessly. Plus either the better map mod or Warburg's paper map. I like nothing about the vanilla interface, but with mods, it can be greatly improved.

To be honest here, vampire attacks will happen whether you fast travel or not. I've had vampire attacks occur after reporting the Watchtower events to BAlgruuf if the "debriefing" ends after about 10pm, and I've gone sleep in the guards bedrolls at Riverwood and had vampires attack within minutes of awakening... even at 9am. avoiding fast travel is NOT a guarantee. Also, I've come across marauding hounds at the stable, and then there is ALWAYS a vampire in Whiterun itself no matter how long you wait before going into the city.

Yeah, the only surefire way to avoid the vampire attacks is either not to use dawnguard or to use a mod that stops the attacks. But avoiding fast travel and resting away from cities so you only approach during daylight hours does reduce the frequency of vampires attacking cities compared to fast traveling or riding carts to cities at night.

oh yeah..i installed the unofficial patches before playing. I'll try out some of these other mods. I did check out Sky UI but didn't want to install too much as I'm not sure what does and does not work with the unofficial patches.

Is it best to use NMM to install most mods and avoid the Steam route?

Yes.

And things like UI or maps are personal preference, don't install any mods the people here can and will shove in your face.

NMM is better than installing through Steam. Wrye Bash or Mod Organizer is better than NMM. Both of those have more features than NMM but also have a higher initial learning curve. NMM will work if you aren't planning a huge load order and don't want to spend a lot of time learning how to use a mod manager.

Just about every mod is compatible with the unofficial patches, so no worries there.

Use LOOT to sort your load order (unless you decide to use Requiem, in which case you can start with LOOT but should make some adjustments manually).

And yes, only install mods that you think you need. Everyone has their own preferences and not everyone enjoys the same things. Personally I cannot stand anything about the vanilla interface, not the map, not the UI, not the HUD, but that's me. If you like the vanilla interface, there is no reason for you to change it.

As for mods just look for mods that you are interested in. Some mods do need the Unofficial Patches, or SkyUI, or SKSE to function. If you prefer the vanilla UI I like I do you can use SkyUI Away. I have not used SkyUI for awhile since my last PC playthrough I did not use any mods that needed MCM (Which is part of SkyUi)

Also Loot and other tools will be helpful if you plan on using quite a few mods.