Sometimes if I hold the arrow keys down while moving about, the action will get "stuck". Meaning, if say I'm moving forward, I release the arrow key, and my Avatar keeps going without any further control from me. Same thing happens when using the left/right arrow keys. The avatar keeps turning in circles like an idiot.
The work around that seems to be working for me to stop the spontaneous movement is tapping all the arrow keys in random order in every direction for a couple seconds. When I stop, the avatar stays stationary and normal control is resumed. I'm not tech savvy enough to to discern weather this is local issue or an issue with the network, but I hope this is enough information to help.
Otherwise, the UB version of SL has given the best game experience I have ever had.
Thank You Lindens!!!