Lose the GOTOs.

Remove existing mappings so you are clear to add the new ones.

Add comments, so that you know it is actually attempting the mappings.

Add error checking, to display the reason the mapping failed.

Abstract the mappings to a UDF (or use one from our UDF library) so that you don't keep writing the same code over and over again.

Something like this (not tested):
Code:
If InGroup("Group1")
MapDrive("J:","\\Server\Share1")
EndIf

If InGroup("Group2")
MapDrive("f:","\\Server\Share2")
MapDrive("g:","\\Server\Share3$")
EndIf

If InGroup("Group3")
MapDrive("m:","\\Server\Share4")
EndIf

Exit 0

Function MapDrive($d,$p)
"Mapping drive "+$d+" to "+$p+"..."
Use $d /delete /persistent
Use $d $p
If @ERROR
" ***ERROR***"+@CRLF
" "+@ERROR+" / "+@SERROR+@CRLF
Else
" Ok."+@CRLF
EndIf
EndFunction