I get strange results when I try to create UDFs in Excel 2007 (using
Vista).

For example, if I name the function any of the following, I get a
#REF! error.
add1
sum1
vol1

However, I don't get such an error if I use
addone
sumone
volone

I never noticed this before in earlier versions of Excel and it was a
pain until I worked out what appeared to be going on.

Any comments about this behaviour (and anything else that may be
associated)? For example, I presume this has been done to preserve
key names, which suggests any key name with just an integer after it
could be suspect.

Thanks,
Chris