Show Userform Only If Hyperlink Does Not Locate File?

On sheet4 is a list of dates and I named that range as UPDATES2013. Each cell in that range is a hyperlink. Sheet1 cell I3 is a data validation list with the named range UPDATES2013 as the list. When a selection from Cell I3 is made I can get it to follow they hyperlink with the code I have. The problem I am having is if there is no file found, then I would like my Userform1 to show. I have tried several different things with the code, but every time I think Im going to get it to work....it doesn't. It either wont show the Userform at all, or it shows it even if the file is found. I am currently putting the code to run the macro on the worksheet module using the worksheet_change event.

One last thing...I also have hyperlinks throughout Sheet1 that will lead to the same files as in the named range UPDATES2013 from sheet4. I need the same thing to happen if they click one of these hyperlinks instead of using the data validation list in Cell I3. Is there a way to make one code that will show Useform1 if a hyperlink is selected and the file cannot be located (whether it be by the individual cells on sheet1...or the data validation list in Cell I3)?Here is the code I am using right now.

VB:
Private Sub Worksheet_Change(ByVal Target As Range)
DoFollow2013 ActiveCell
End Sub [code]....