One of my clients has this startup problem.
After his system boots, he gets 8 messages about a file or registry reference missing. Clicking OK on each popped up window gets past all of the reported errors. See this link for details: http://rouley.com/pub/it/StartupErrors.mht
Currently, I am studying the startup sequence of WinXP, to see if I can find the offending file or the line item in the startup file that is causing this problem. Using msconfig, I turned off win.ini, but that did not resolve the problem.
Instead of bothering my neighbor with trial and error ideas, I thought someone here might have an idea on what might be causing this behavior.
We've used registry cleaning tools, cleared out the StartUp folder in Programs, booted without win.ini - thus far, the errors are still reported - this happens while the desktop icons are being created, so I am thinking it is something after win.ini and after desktop.ini are loaded. Windows works just fine after 8 clicks on the OK buttons, but perfomance is SLOW. Of course, we've run virus and spyware scans along with the registry cleaner, with nothing found and no improvement.
Ideas, thoughts, suggestions?