F9 breaks Shift-F9 for XLL functions
 

I'm having with our .XLL DLL where it is working fine if you:

pressing shift-F9 (the whole sheet recalculates, this can be done multiple
times, and works fine).

Once F9 is pressed, it computes ONCE, but then if you press shift-F9 it does
not calculate anymore ?!?!?

Basically F9 stops any more calculation from occuring. What is going on???


I'm writing a C/C++ DLL (i.e. XLL) and running against Office 2003 (same
behaviour on Office 2000) and calculation is set to "manual".

Any help would be much appreciated.

Warren