Custom Lookup UDF Issue

I've got an odd issue where a UDF that does a lookup for data into some named ranges goes to #Value when some macros are run in the workbook that do not have anything to do with the UDF lookup. I've included an example file with instructions. If anyone has any idea what is causing this issue it would be greatly appreciated.

Thanks!

This issue has also been posted at: http://www.vbaexpress.com/forum/showthread.php?t=39682