Automatic link updates had to be disabled because the file will lock up some
machines that just can't handle updating 2700 links. That wasn't a problem
until I added a record to one of the source files (while the workbook with
the links is closed) and the next time we open the workbook, when vlookup
attempts to retrieve values from that record it returns #N/A until the link
is updated.

Any idea why vlookup won't read newly entered data from a source file that
was edited before the workbook containing the lookup value was opened?

Every other record in the source will display it's lookup values just
correctly and accurately.