Run MSCONFIG. Go to the Services tab. Check the box at the bottom which says "Hide all Microsoft services". Now go through the services which are listed in the window, and uncheck all of them except for those you feel you must have. Click Apply, then reboot the computer and log back into Windows in Normal mode. Then shut down and reboot again to see if the problem has been solved.
Hopefully this solved the problem.
If it did solve the problem:
If that solved the problem, you could either leave well enough alone, or you could reenable the services you unchecked, one or two at a time (and then reboot twice), to see what specifically caused the problem. Once you have narrowed it down to the one or two problematic services, leave them unchecked to eliminate the problem. Or perhaps uninstall / reinstall the associated program.
If it did not solve the problem:
If that did not solve the problem, then you will need to uncheck more of the non-Microsoft services (then reboot twice), until the problem is solved. At that point, you can leave well enough alone, or you can re-enable the services which you previously disabled (except for the last one you disabled, which apparently was causing the problem), and then reboot twice to see if the problem is still solved. When you have narrowed it down to one or two misbehaved services, either leave them disabled in MSCONFIG, or uninstall / reinstall the associated programs.
Keep in mind that each of these services provides some functionality to Windows. If you leave something unchecked, then that functionality won't be available in Windows. For example, Adobe Acrobat may have a service which always runs. It might check for updates and install them if available. By disabling this service, the Adobe auto-updater won't run. That may be perfectly fine with you; but you need to be aware that this is the sort of thing that will happen if you disable services in MSCONFIG.
The reason you reboot twice after each change is because the change won't take effect till after you reboot once; you must then reboot again to see if the change you made fixed the problem.
