By default, the Windows NT 4.0 shell creates 1 process with the Taskbar and Desktop as one thread and each instance of explorer in 1 additional thread. A failure in any thread will affect the entire process.
If you have at least 24 Meg of RAM and a fast Pentium, you can create a separate process for the Desktop/Taskbar and 1 for each instance of explorer by editing the registry at:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer
and adding value DesktopProcess (REG_DWORD). Set it to 1 and reboot.
On my dual processor, this seems to give snappier 
Desktop performance.
NOTE: You can not have Active Desktop with this hack.
NOTE: In Windows NT 5.x, the default action is to have 1 instance of Explorer.exe. Implementing this tip appears to be identical to checking the My Computer / Tools / Folder Options / View / Launch folder windows in a separate process box, which invokes one additional instance of Explorer.exe for all Windows Explorer windows, a total of 2 processes. I DO NOT recommend implementing this tip for Windows NT 5.x, as it's functionality may change with a service pack. See Q306117 - Mapped Drives in Windows Explorer May Retain the Name of a Disconnected Drive. If you wish to implement the Launch folder windows in a separate process function using the registry, Copy / Paste the following to a SFP.REG file and Merge it with the registry:
REGEDIT4
\[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\DesktopProcess\]
"Type"="checkbox"
"Text"="Launch folder windows in a separate process"
"HKeyRoot"=dword:80000001
"RegPath"="Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\Advanced"
"ValueName"="SeparateProcess"
"CheckedValue"=dword:00000001
"UncheckedValue"=dword:00000000
"DefaultValue"=dword:00000000
"HelpID"="shell.hlp#51079"
\[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\DesktopProcess\Policy\]
\[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\DesktopProcess\Policy\SeparateProcess\]
@=""
\[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced\]
"SeparateProcess"=dword:00000001
