persistent network shares and passwords

I have 2 Win2k workstations. A & B. I have mapped the Administrative share c$ of B on computer A.
I made the mapping on A using the typical command:

net use Z: \\B\c$ password /user:B\Administrator /persistent:yes

Whenever I reboot A, I am always asked for the password for the share \\B\c$ , like..
“incorrect password or username for \\B\c$…. You last logged on to this computer as A\Administrator”

There must be some way out of this, as I am not asked passwords for network shares I have on other servers (these servers are maintained by professional admins…). Computer B hass a fairly virgin Windows configuration, so I have not played around with its settings.

All the accounts involved have administrator rights.

So any way I can map \\B\c$ without having to enter my password each time ?

-misterIT