I had issues sharing drives a few years back when I changed my system over to Vista, perhaps its the same issue.
If you are a peer to peer network as most small networks are and you wish to share I had to create an account for each user that wanted to access shares on each machine, that's the only way I could get it to work right. Example:
- Machine 1 has a user named Dude, and the Docs folder is shared with everyone.
- Machine 2 has a user named Dudette, and her Docs folder is shared with everyone.
On Machine 1 create an additional user called Dudette, and on Machine 2 create an additional user called Dude. That's what I had to to between Vista and XP machines to get my workgroup shares to function properly.
Hopefully, Windows 7's Homegroup will solve all these issues... but I havent had a chance to try!