My guess is that you have something like:
If KeyAscii = 13 Then
SendKeys "{TAB}"
End If
in the Keypress Event and when you hit enter to tab you then here the beep. If so change to:
If KeyAscii = 13 Then
SendKeys "{TAB}"
KeyAscii = 0
End If
If not then you need to explain that sound a little clearer.
"Two strings walk into a bar. The first string says to the bartender: 'Bartender, I'll have a beer. u.5n$x5t?*&4ru!2[sACC~ErJ'. The second string says: 'Pardon my friend, he isn't NULL terminated'."