We have a Dell OptiPlex 745 desktop system which will often fail to boot after a restart. The diagnostic lights show a 1-2-3 pattern which has no definitive solution in the manual. Pressing the power button shuts down the system immediately after this particular boot failure. Pressing the power button from an power off condition always results in a successful boot. This problem only occurs after a Windows restart and then not with every restart but intermittently.
I have Dell optiplex 745 with device number H0KS3D1. The problem with my computer is some times it does not start but the fan runs and only after many trial it starts and sometime it gives me different colors. So how can i fix this problem.