When you initiate a connection to a shared network resource by using the Universal Naming Convention (UNC) format \\server\, the OS passes the connection request to the Multiple UNC Provider (MUP--mup.sys). MUP then identifies the network redirector that can perform the connection. If you're logged on to a system that connects to DFS shares or performs Active Directory (AD) searches, accesses Macintosh files in a Services for Macintosh (SFM) partition, or connects to Novell NetWare or UNIX-based resources, the local system has four network redirectors, one for each resource: a DFS client, an SFM client, a NetWare client, and a UNIX client. When MUP receives a request for a UNC-formatted resource, it queries all four of these redirectors to see which component should manage the request. On a system with multiple clients, you might notice a delay between when you request the resource and when the system responds because MUP waits for all network redirectors to respond before initiating the connection. The Windows 2000 Service Pack 4 (SP4) version of MUP has a bug that can crash a Win2K system when the DFS client is disabled. When you install a Win2K system, setup enables the DFS client by default. If you don’t publish DFS shares or use AD searches, you can disable the DFS client by stopping the related DFS service and setting the startup type to disabled. You can also stop the DFS client programmatically or with a registry edit. When this MUP bug is the cause of the system crash, you'll see a Stop 0x1E error. The system failure typically occurs when you reboot after completing an SP4 upgrade, but it can also occur when you request access to a UNC-formatted shared resource on an SP4 system on which the DFS client is disabled. For more information about the MUP bug, see the Microsoft article "Stop 0x1E Error in Mup.sys After You Apply Windows 2000 SP4" (http://support.microsoft.com/?kbid=824288). To work around the blue screen, enable the DFS client with a registry edit, a registry script, or a Group Policy Object (GPO). Locate the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Mup registry subkey, and change the DisableDfs (of type REG_DWORD) value entry from 1 (DFS client is disabled) to zero (DFS client is enabled). To avoid MUP-based system crashes, call Microsoft Product Support Services (PSS) and ask for the new version of mup.sys (5.0.2195.6774) with a file release date of July 11. Assuming you don't enable the DFS client, you can install the hotfix on Win2K SP3 systems before upgrading to SP4 and on already upgraded SP4 systems. To install the hotfix on SP4 systems, you need to replace driver files that are open when the system is running. The only way to replace open files is to boot to the Recovery Console (RC); you can install the RC on the local system and you can also boot the RC from a standard CD-ROM installation disk. At the system prompt, copy the previous version of mup.sys, in the %systemroot%\$NTServicePackUninstall$ directory, to the %systemroot%\system32\drivers directory, then reboot. This step effectively restores the SP3 version into the OS. Then, install the hotfix and reboot a second time.

SP4 and SP3 Terminal Server Bug Fix Here’s a Win2K Server Terminal Services bug that didn't get fixed in SP4 and thus can occur on both SP4 and SP3 systems. When a Terminal Services client logs on or off a client or console session, a server-based disk write-caching deadlock makes the server unresponsive for several seconds or longer, during which time the server can't process any other input. According to Microsoft, when the delay occurs, the client might show any of the following symptoms:
• When a user is typing a document, characters don't appear on the screen until the server recovers from the deadlock.
• Keyboard input and mouse input are queued but not processed until the pause ends.
• Live Performance Monitor graphs have missing data points during the pause.
• All running programs appear to stop responding or hang during this pause.
• When Spooler is under a load from a large number of users, you'll see high CPU usage.

If you opt to install this fix, you can see the extensive list of modified files in the Microsoft article "Terminal Server and Connected Terminal Services Clients Pause When a Terminal Services Client Logs On or Logs Off" (http://support.microsoft.com/?kbid=324446). After you install the patch, you must also enable Power Protect on all hard disks on the Terminal Services system. You can query and change the Power Protect status of hard disks by using the dskcache.exe utility, which is available only from PSS. The Microsoft article "Obtain the Dskcache.exe Tool to Configure the 'Power Protected' Write Cache Option" (http://support.microsoft.com/?kbid=811392) describes how this utility works.

Win2K SP4 Citrix Logon Delay
Have you noticed logon delays on Citrix clients after an SP4 upgrade? A printer redirection bug can cause delays of 5 to 30 minutes on systems running Terminal Services and either Citrix MetaFrame or Citrix 1.8. This problem occurs on systems on which you redirect a print queue to a local printer on the client system. If this description matches your configuration, you can call PSS and ask for the bug fix, which includes updated versions of 15 core OS files including msgina.dll, kernel32.dll, win32k.sys, and Winlogon. Most of the files in this patch have release dates of July 17, and you can get the update only from PSS. When you call, cite the Microsoft article "Very Long Logon Time When You Try to Connect to Citrix MetaFrame or Citrix 1.8" (http://support.microsoft.com/?kbid=824309) as a reference.

Windows Explorer Bug Fix
Every now and then, when you right-click a file to access the drop-down menu in either Windows XP or Win2K, Windows Explorer fails with the error message Windows Explorer has encountered a problem and needs to close. We are sorry for the inconvenience. Microsoft doesn't identify the bug that causes Windows Explorer to fail, but the company states that the problem occurs on XP SP1 and Win2K SP4 systems that run Windows Explorer 6.0.2800.1221. If this problem occurs frequently on your systems, you should see Dr. Watson messages about Windows Explorer in the System log. To correct the problem, call PSS and ask for the bug fix on either or both platforms; the fix updates three files: ole32.dll, rpcrt4.dll, and rpcss.dll. The updated files for XP have a file release date of July 22, and the Win2K versions have a file release date of July 21. You must reboot the system after you install the hotfix. For more information, read the Microsoft article "Windows Explorer Quits Unexpectedly or You Receive an Error Message When You Right-Click a File" (http://support.microsoft.com/?kbid=824136).