I'm 99% sure this was not due to TD, but still something I thought to pass along to everyone else.
While running b4 in windowed mode, I switched to a screen that references an Excel htm file. I was updating the file (a points sheet, and we don't have internet at the location), saved it and left it open, then went back to TD. I went from sheet 1 to sheet 2, and it froze.
I did something similar, but with the file closed, and it worked perfectly, so I believe it's because I had the file open still - I was updating how the file looked.
Again, I'm 99% sure it was due to the file being open and not TD.
Mike