Ok, try typing Configsys in the box at the bottom of the start menu and press return, you should then get a box up with some tabs on it, go to the start up one and untick all but the microsoft ones, click apply and then OK, close the window and re-boot, you'll get an error message just tell it ok, you should then be able to install process explorer. Re-tick one or two of the startup programs, reboot start process ex and see what happens, repeat as required. ( Or make a note of the programs you untick and use the start menu to start them one at a time.)