After having a weird (not so much different from the normal vanilla game...buggy as it is but still.) experience in my main game at the end of the Stormcloak rebellion quest line in Solitude last night and the bug everyone is reporting being related to going with the Storrmcloak guy at the beginning I decided to test for myself.
Last night when the Solitude raid began I had thought that I remembered the Imperials would pour out endlessly to fight until you enter the castle but that is not what happened in my game after the initial waves of Imperials were wiped out Ulfric, Galmar& everyone just sheathed their weapons and stood around until I went through the door into the castle. I waited and ran around a Looooooooooog time before this as I had called a Dragon and wanted to witness a huge epic battle since the imperials would keep coming...no dice. So I finally went into the castle played out the end game and another odd thing... The battle music kept playing endlessly no matter where I went in Solitude, even AFTER the battle and aftermath where Ulfric makes his speech and everyone stands down outside the castle.
The battle music FINALLY cut off when I fast traveled to another city and it loaded me there.
So upon seeing the posts here I just tried to replay the beginning with a new character... When the gate to Helgin opened the horse never stopped walking and almost turned over the prisoner cart and got hung upright on the gate door walking endlessly into nothing and the game would never move past it as the cart couldn't enter the town.
So then I used my "just before character creation save to jump ahead right before you choose to follow the Stormcloak soldier and once I hit the point where we're supposed to hide and ambush the Imperials everyone stops and stands there until I enter the room and then they just stand there while me and Mr Storm cloak murder them.
This mod has improved my games smoothness SOOOOO much I hope a workaround can be found for it.
I am an Win 7/64 Athalon X2 dual core 939 user with latest version of Skyrim and other than this I am using only various texture mods and Realistic Colors and Real Nights v14 with HDR