I have been running into this problem lately. Seems to happen for several different reasons. I have a friend that it used to happen to frequently, more often when she was on a poor connection in various hotels. So I think there it was something to do wtih connection issues. I can not however pin down why it happens to me.
What I can say is that wearing an overlayer (jacket/skirt are best) of a clear clothing item then rebaking with that on seems to help many times. Clear clothing is not hard to make, but if you'd rather just come pick up the set I made, I have placed it up for free in the lobby of my store near the TP signs. Look for a pink sign...slurl below, or just search SVU in places or classifieds.
http://slurl.com/secondlife/Animatum/142/136/325