After installing various software products directly from executable-install-files an "svchost.exe" error is encountered at system shutdown.  The error references various memory locations that cannot be written to.  System restore correctly resets the system and the error dissapears.  If I use
Add/Remove programs to locate and install the executable the errors do not manifest at system shutdown.  The error may also, but not always, appears after an application hangs the system.

System is a new Dell 8300  2.8 Ghz processor running WindowsXP Professional.