Diagnostic boot question

I keep getting an error message, "The requested resource is in use" on any
administrative user account, but not on the Administrator account. This
error happens when I try to run a .exe file, and run just about most things.
When I boot the system in Safe Boot - Minimal, everything works. When I boot
in Diagnostic startup, when very little more is running, the error is there.
The only difference between these I can tell when I run task manager is that
ONENOTEM.EXE and upeksvr.exe are running as processes, and slsvc, gpsvc, and
AppInfo are running as services in Diagnostic startup. Could one of these be
the cause, and what should I do to find out?

Thanks,
Mark