Help! My pc has decided to stop shutting down or restarting using the 'start bar/turn off computer windows. It will go into standby but the only way to turn it right off is by using the main power button on the base unit.
You say it will go into standby , I will guess at a power management problem , try this. Disable power management by opening control panel , select system icon , when the system properties dialog box appears , select device manager tab , then click the '+' next to system devices , highlight advanced power management and click the properties button , when the advanced power management support properties dialog box appears , select the general tab , tick 'Disable in this hardware profile' , click OK , now try to shutdown as normal.If this fixes your problem leave the settings as you've just changed them
This can happen when a programme has been changed and is not able then to close down properly, have you recently added, altered or adjusted any software?. You might try doing a system restore to a earlier time if you know when approximately the problem occurred.
Have you tried the help and support section ? Start , help and support , click fixing a problem (bottom left), click troubleshooting problems , under overviews articles and tutorials , click list of troubleshooters , click startup/shutdown and go through these as another option.