Excel 2001 crashes on worksheet functions

[Iconomou Jiannis]

If someone has ever faced a similar problem and can help
me out....
I am using the Excel program from the Office 2001 for Mac.
My Mac is a G4 450MHz Dual proccessor with 128Mb ram and
10Gb HD.
The problem I have is that although the XL program
operates smoothly without no problems whenever I wanna
insert a function it crushes!!! and the display freezes!
Sometimes I get a Bomb error 2 sometimes a 3!!!
The most unusual however is that the program crashes on
the 2nd insert of a function...
To make myself clear:
On a worksheet I select tools->Insert->Function(whatever
function...) and I get the expected result, but if I am
going to to again Tools->Insertr->Function ...The system
crashes!!!

I am desperate because although I tried deleting the
preferences file...re-installed office as well as
assigned more memory to the application(exact multiple of
the minimum requirements, e.g. min 6 assigned 12).. the
problem still remains!

Hopefully I will be able to find a solution throughout
the newsgroup...

Thank you in advance for you time
Jiannis