Sharing Vista from XP - some partitions denied

Running newly setup Dell 546 have Vista Home Premium (64)
Networking and Sharing Control configured as Private and all Sharing
'On\\" except Password. Workgroup name changed to MSHOME to match my XP.
No problem mapping to my XP's three partitions.

Problem is a bit different from post of a few hours ago \\"Sharing
Vista folder in XP: 'access denied' for a folder I create.\\" In my XP
can only map to my 546's E and F drives, not C and D; get the message
[mapped drive]:\ is not accessible, access is denied. Have checked all
four drives (partitions) on the 546 and all indicated they are shared
with identical permissions. Appreciate help.


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Ed Bitzer