There seems to be an inability to share an entire hard drive in Windows Vista over a network. Even if you set the permissions to share it across, other computers are given an error when they attempt to access the shared drive.
The solution is to only share folder within the hard drive, which Vista seems to have no issues with sharing individually. This seems to be a Vista-only problem, though it intermittently happened in XP, usually as the result of a software firewall blocking access.
Microsoft seems to have decided it’s too big of a security risk to let you share an entire hard drive.
To share a folder in Windows Vista…
1. Right-click the folder, choose “Share”
2. In the drop-down menu, choose the users you want to share the folder with.
3. Under the “Permission Level” heading, click to choose the level of access you want each user to have.
4. Click “ok”, then “continue” on the User Account Control prompt.
If you want the old-skool approach in Vista
1. Right-click the folder, select “properties”
2. on the “Sharing” tab, click “advanced permissions”, then “continue” on the User Account Control prompt.
3. Put a check in the box next to “Share this folder”, then click the “permissions” button
4. For each user, type in the account name and press enter, then choose their permissions