Microsoft update may fix this issue. Check this link for the update.
Windows Vista Update and download
10. A "Web Services on Devices"-based printer appears as Offline after you
wake a Windows Vista-based computer from sleep ....
Bob Lin, MS-MVP, MCSE & CNE
Networking, Internet, Routing, VPN Troubleshooting on
How to Setup Windows, Network, VPN & Remote Access on
"SamA" <SamA@discussions.microsoft.com> wrote in message
>I have 2 Vista machines, the primary machine is the print server and
> USB external drive where backups go for both the primary and the secondary
> Both the primary and secondary machine have the same user named, both have
> no password associated with the account. When I try to share the USB drive
> with the secondary machine it fails because the accound on the primary
> machine doesn't have a password associated with it. So, I create a
> on the primary machine account. One the secondary machine I manually
> the USB drive and click the reconnect after a reboot.
> When I reboot the secondary machine the USB drive is not mounted
> automatically I have to manually enter the login and password. I also
> the ability to print on the secondary machine until I mount the USB drive.
> Is there any way to make sure that the drive and printer are always
> available on the secondary machine even after a reboot?