*** MINOR COMPANION QUEST SPOILERZ ***
I just had the weirdest bug.
I finished the companion quest line as one of the first things i did in Skyrim. 90 hours later in the game i returned to the Companion's base to find Vilkas and train some 2handed weapon (almost lvl 50... almost). Anyway, i enter the Hall and there is no one there. I exit though the back and Ria and Vilkas attack me. The rest just stands there. I run around not trying to do anything while suddenly Skjor comes running by in his underwear, who as we all know died during the companion's quest. He has 2 guards running after him, who try to attack him. When i talk to him he says i'm a whelp and i have much to learn. My last save was ages ago, so i reloaded the auto-save when i entered the Companion hall.
Now, instead of going outside i decided to stay inside and wait. Maybe that would solve the problem. I wait 3 hours and everyone is inside. Vilkas and Ria immediately start attacking me. Ria gets damage because of the 10% reflect chance heavy armor perk. It's only a tiny bit of damage and she runs away with her hands above her head saying that she yields. Vilkas is still swinging away. I give him one good swing with my warhammer and immediately take down about 2/3 of his health. He then sheathes his weapon and talks to me. I can do the training and i'm happy. I then exit the conversation and he talks to me again.... and again... and again... I try running away and he runs after me. In the next conversation i suddenly see underwear Skjor running circles through the Hall, followed by Ria, who is also still running in sheer terror. I left he conversation, opened the front door and ran as fast as i could. As far as i know, Vilkas isn't following me.
I was laughing the entire time, but seeing Skjor was pretty freaky.
Not having much trouble with bugs though, this was the first major one. I did feel the need to share though