Excel 11.3.7 behaving poorly under Leopard (10.5.0 and 10.5.1)

[Ed]

I've noticed an odd problem running Excel 11.3.7 on my Mac Pro (2x2.66
GHz Xeon with 2 GB of RAM). Occasionally when trying to type data into
the formula bar or a dialog box my keyboard freezes for 10 to 45
seconds. By this I mean that I cannot type anything. My mouse, which
is plugged into my keyboard, still works. And, I can use my keyboard
in other applications. So, I assume this is a problem with Excel and
Leopard on the Mac Pro. I did not have this issue on previous editions
of the Mac OS.

Has anyone else experienced this problem? Is there a fix?

Thanks,

EV