I have a worksheet which uses data validation in one column (Column A) to
select a customer name and then a VLOOKUP formula in the next column (Column
B) to return the corresponding customer number. This was working just fine
but within the past 30 minutes, when I choose a customer name in Column A,
the B value is not returned until I either save the spreadsheet or click on
the formula in the formula bar and then press enter. I did not change the
formula in either A or B.

Does anyone have any experience with this or know of a workaround? The
spreadsheet also uses INDEX and MATCH elsewhere with a lot of tables (which
are not used in the above scenario) and so I'm reluctant to recreate this
from scratch.

Thanks...