cannot access to a shared drive/files

I have a NT workstation 4.0 with SP6 with 2 drives on it, 1 fat and 1 ntfs. This machine is on the network because I can ping to it.
I shared both drives and grant everybody, all domain users with full access right. I can see this machine from the network neighborhood though it takes a long to browse it. However, I wasn’t be able, and nobody either, can access to that shared dirves. This is the message tha I got “\\yourcomputer\sharedfolder is not accessible. The session was cancelled”. So, what could cause it and what else can I look for it. Please help.