Ick - permanent loops bad.

 Code:
$iInterval=0.1  ; Check for presence every 10th of a second
$iMaxWait=10.0	; Don't wait any more than 10 seconds

Use x: "\\server\share"
While @ERROR=0 AND Not Exist("x:\") AND $iMaxWait>0
    Sleep $iInterval
    $iMaxWait=$iMaxWait-$iInterVal
Loop

If Exist("x:\")
	;Label script goes here
EndIf