Do a 'paste special' operation and paste as plain text. For ease of use, I recommend pinning the 'paste special' button to the Quick Access toolbar.
Sometimes Access gets confused when you let it guess what you're pasting. Pasting as plain text is the best way to force it to work.
Edit
Example Code for Right Click Menu
Public Function CreateGeneralClipBoardMenu()
On Error Resume Next
CommandBars("GeneralClipboardMenu").Delete
Dim cmb As Office.CommandBar
Set cmb = CommandBars.Add("GeneralClipboardMenu", msoBarPopup, False, False)
With cmb
.Controls.Add msoControlButton, 21, , , True ' Cut
.Controls.Add msoControlButton, 19, , , True ' Copy
.Controls.Add msoControlButton, 755, , , True ' Paste Special
End With
Set cmb = Nothing
End Function
The ID# 755 is a magic number for Paste Special, and I found it on this list: http://support.microsoft.com/kb/213552
Where to set it in Access 2013. Access Options - Current Database - Shortcut Ribbon Bar