I got it. You can update a hyperlink field data type with just a string. You need to include the # symbol!

VB Code:
  1. Do While Not rst.EOF

  2.         rst.Edit

  3.         'INCORRECT: rst![thelink] = "K:\HOME\rob\ylds\" & rst![StratumLink] & ".xls"

  4.         rst![thelink] = "#K:\HOME\rob\ylds\" & rst![StratumLink] & ".xls#"

  5.         rst.Update

  6.         rst.MoveNext

  7.     Loop

ww