[Widowmaker]

I went to XP 64 a while ago and had the same problem..

I cant remember EXACTLY what fixed it..
but it was updating a component..

I believe it was one of these..

Sun java runtime

.net framework 2.0 SPK2
.net framework 3.0 SPK2

MS C++ runtimes 2005 redistributable

I really wish I could be more specific...
but I know I had that problem and I know it was fixed by updating a component like that.
I BELIEVE it was one of those I listed but I can't remember exactly.