Hi there, I have a set of macros that run and then I need to turn calc back
on. This all worked fine until I introduced a UserForm (that I use to control
the flow of the work and for monitoring). Now, whenever I execute
Application.Calculation = -4105
either by a code line or into the immediate window Excel hangs for anything
up to 3 or 4 minutes (the status bar says "Calculating Cells 100%) and then
the hourglass comes up and Excel is completely frozen. From there the only
way out is to crash it through the Task Manager.

BTW, the UserForm is brought up with Show 0 so that it's modal.

Oddly enough, sometimes it just requires me to activate the Task Manager,
and I can then go back to the spreadsheet and continue working.

Even more odd is that in the immediate window I can either calculate a sheet
or just do Calculate and it only takes a moment (as you would expect).

What can cause this behaviour (anything to do with UserForms?) and how can I
solve it please? Regards, Brett.