I recently encountered a situation in which a customer's Windows 98 PC couldn't log on to the shares on the customer's Windows XP Professional Edition PC. The customer had a peer-to-peer (P2P) environment, and the XP PC could navigate shares on the Win98 PC. When the Win98 PC tried to connect to the XP PC's shares, an Enter Network Password dialog box opened and showed the message You must supply a password to make this connection: Resource: \\computername\IPC$, with a field to enter a password. As a test, I tried logging on to the Win98 PC as different users. The same dialog box opened each time I tried to connect to the XP PC's shares.
The Microsoft article "Unable to Connect to Network Share When Netlogon Service Is Not Started" (http://support.microsoft.com/?kbid=262916) discusses this problem in the context of a Windows 9x computer connecting to a Windows 2000 Professional computer's shares. Although stopping and restarting the service might work in Win2K, doing so didn't correct the problem of Win9x PCs connecting to XP shares.
To determine whether the Netlogon service was working on the XP computer, I ran the Netstat –a command and paid particular attention to the following line in the output: TCP >> XPPC:netbios-ssn >> XPPC:0 >> LISTENING. Note that netbios-ssn is commonly known as 139/TCP—NetBIOS Session Services. The LISTENING output showed that the Netlogon service was working, so I figured an authentication problem existed. (For more information about common ports, see the Microsoft articles "A List of the Windows Server Domain Controller Default Ports" at http://support.microsoft.com/?kbid=289241 and "Windows NT, Terminal Server, and Microsoft Exchange Services Use TCP/IP Ports" at http://support.microsoft.com/?kbid=150543 or browse to C:\winnt\system32\drivers\etc\services.)
I tried rebooting the XP and Win98 machines several times, checking the share and NTFS permissions on the XP machine's share directories. I even created new shares and tried to access them. One solution would have been to delete and recreate the Win98 user on the XP machine—but I would have spent the rest of the day updating the shares and permissions. While I was contemplating this task, I suddenly remembered an old Windows for Workgroups (WFW) 3.11 trick: Simply reenter the user's password on the computer that holds the shares.
I reentered the Win98 user's nonexpiring password in the Win98 user's account on the XP computer. Voilà! The Win98 user could again access the shares on the XP computer. This fix was necessary for all the Win98 users who had a user account on the XP computer.