Hi Glenn \:\)

Thank you for your input, as the exist checking was also something I was a bit unclear on. Modified code below.

 Code:
;
CALL '\\Networkserver\Networkshare\ComputerinGroup.udf'
;
$Access2k10 = '\\Networkserver\Networkshare\O2k10-Access.cmd'
$A2k10Check = 'c:\scripts\Installed\A2k10.txt'
$MessageHeader = ' Software is being installed to your computer ' 
$Reboot = 0
;
If ComputerinGroup ("Access2k10") AND NOT EXIST ($A2k10Check) 
	MessageBox ("$MessageHeader","               Access 2010 is being installed / upgraded...               ",0,30)
	$Reboot = 1
	RUN $Access2k10
		DO
			Sleep 10
		Until EXIST ($A2k10Check)
EndIf
;
If $Reboot = 1 
	Shutdown ("", "The upgrades performed on your computer require a reboot, that will occur in 20 seconds.", 20, 1, 1) 
Else 
Exit


You also have an excellent point about possible forever loop if there's a failure in the called CMD. However, I'm closing my eyes, and ignoring that potential problem for now.