Source: http://support.microsoft.com/kb/891861

Error messages
You may receive one of the following error messages when you visit the Windows Update Web site:
MSXML3.DLL File Not Found
Error 0x80244001
Error 0x800700C1

You receive a "Stop 0x000001E" error message when you restart the computer after you install Update Rollup 1 for Windows 2000 SP4

You may receive the following error message when you restart the computer after you install Update Rollup 1 for Windows 2000 SP4:
Stop 0x000001E

On a computer that uses dynamic disks, two system drives may appear after you install Update Rollup 1 for Windows 2000 SP4

You cannot save files from Microsoft Office programs directly to a floppy disk

You cannot connect to a Citrix server that has ICA sessions after you install Microsoft Update Rollup 1 for Windows 2000

An Exchange 5.5 message transfer agent (MTA) that uses an X.400 connector on Windows 2000 SP4 may stop transferring mail after you install Microsoft Update Rollup 1 for Windows 2000

After customers install Microsoft Update Rollup 1 for Windows 2000 SP4, customers who use Sophos Anti-Virus for Windows version 5 may experience a delay when they log on to their networks. A computer may take 15 minutes to log on to the network when the following message appears:
preparing network connections

Some versions of Internet Security Systems products may not start after you install Microsoft Update Rollup 1 for Windows 2000.