Excel stops responding when I enter a formula.

Problem can be due to a number of ways. To find the one that is bothering you, can you go to the formula tab and use "insert formula" ?
if not, please set calculation mode to "manual" (also on formula tab) and retry

if it still doesn't work in manual calculation mode, please start excel in safe mode and try again.

starting in safe mode can be done by executing (from command prompt or 'run' from start menu):
"C:\Program Files\Microsoft Office\Office14\excel.exe" /s
or open with while pressing the Control key on you keyboard.

if the problem does not exist in safe mode, it most likely will be caused by an add-in

I have tried safe mode, and the problem still exists.
It's still crashing.

Thanks,
PJ

Do you get the same problems when copy-pasting formulae and using VBA macro code to generate formulae ?

Copy-pasting formulae still causes the crash.

As far as I'm aware, no VBA macro code is being used so I can't test this...
I may be wrong though, so apologies that. My knowledge of Excel isn't amazing.

Thanks,
PJ

or when you type

^=sum([...])

and then globally replace "^" with "" (nothing)

as for the vba macro, you could open the vba editor by pressing [Alt-F11]. then open the vba code section of the worksheet you currently have active, and copy-past this subroutine in the vba editor:

Sub test_generate_macro()
    Range("A1").Formula = "=sum(A2:A3)"
End Sub

Select allOpen in new window

place the cursor inside the subroutine and press [F5] to execute it.

ugg office connector eh?

We found out the issue internally and explained what it was for others to know if they had the same problem