Physics Simulation Forum

Hi all,
I have implemented an implicit cloth sim based on the large steps in cloth sim paper. I have run int oa problem though. When the simulation starts, the cloth animates fine as shown in the vdo below.
http://www.youtube.com/watch?v=oY_T4BMXHIo

However, after a while, it starts to move left and right alternately as if I have wind blowing left and right when i have no external force in the scene as shown in the vdo below.
http://www.youtube.com/watch?v=7v8_MCLFHKI

What may be causing this? Any ideas?