I’ve used Audacity with no probs in the past.
I have windows 7 & 64 bit processor.
I’ve started getting a problem that’s so weird it would be hard to put into words !
So it’s best illustrated with this video http://www.youtube.com/watch?v=w65iNCP52bw
I uninstalled earlier version & downloaded 2.0.1 to see if fixed it but made no difference.
Overdub is on
I use a Line 6 UX2 with POD farm.
That certainly shows the problem.
Check all of the items listed in “Why is my new track out of sync with the previous ones, or sounds crackly or at wrong pitch”