Also, if there are spaces in the name don't forget the double quotes ... like "C:\Program Files" ... If you're executing from xp_cmdshell you might try a DIR command in xp_cmdshel to check things out security-wise. I'd also stay away from mapped drives since SQL Server is only made aware of them each time the service is started - UNCs are the way to go.
RegardsRudy KomacsarSenior Database Administrator"Ave Caesar! - Morituri te salutamus."