I have a user defined function contained within a Module Function
procedure in Workbook 1.

When I have a second workbook open, which has it's own macros and VBA
code - totally unrelated to Workbook 1, i.e. no links or similarly
named procedures, the second workbook seems to want to run through the
UDF contained in Wb 1.

In case it matters the same UDF is also held in my Personal.xls
workbook although it is the UDF in Wb1 that is being used.

How can I prevent the second workbook seeming to want to use the UDF in
the 1st Wb?

Usual TIA