I have the same problem.
The example given by the initial post is right on the money - any simple division in vbscript can kick this off.
Never happened until we moved our website to Windows 2003. Win NT, Win 2000 and Win XP do not get the error.
As the first poster pointed out - its not an "arithmetic overflow" like trying to cast a large number into an int or dividing by zero - the error only says "overflow".
We have extensive logging turned on for this -The values can be as simple as 1 divided by 1.
Once this starts happening the app pool is basically shot - It will happen everytime. Its unprdeictable as to when it will happen.
We have MOM set to recycle the app pool whenever we see this. We have been forced to automatically recycle our app pool every 45 minutes - but we still get the problem occassionly.
I too played around with cdbl and clng hoping it would make the problem go away - alas no luck.
I'm going to move the division operation inside of a vb
dll. I'll post here if it makes an improvement.