After I switch my computer off I can't switch it back on again for about 5 hours. This has only recently started and to my knowledge I have not changed any settings. Anybody any ideas what is causing this?

What's your windows .. and what error does it give when you start your computer. Does your computer POST every time you start it??

and does it take it an unusally long time to Shut Down? Try waiting about 5 mins after complete shutdown, then disconnect the Power Cord, wait 30 seconds, plug it back and try to Boot.

Hello there,

When you say that you can't turn it on again for like five hours, is this because it is still shutting down?

If so, have you recently installed any new software, particularily any Norton products? Norton Antivirus seems to GREATLY slow down the speed of shut downs because it has an option thats default is on right out of the box. This is a VERY common problem for many people when shutting down after the software has been installed.

Anyways, if you did recently install Norton Antivirus, or the problems have started since installing it go into the "options" and then into the "auto protect" drop down menu and then into "advanced". From here you will want to uncheck "Scan floppy disk in A: for boot viruses when shutting down"

Regards,
-Emily

takes too long to shut off

You might want to review this article from MicroSoft and download and install UPHClean
http://support.microsoft.com/kb/837115

I have also found that excessive com devices can often cause this problem. I do have a question for you though. Immediately after you reboot shut the system down. Does it still take 5hrs to shutdown or does it shutdown immediately.

In my case I had Zoom Fax Modem, an ethernet connection on the MB, and a wireless D-Link PCI card installed. I have since uninstalled the Zoom Fax Modem (add / remove hardware) and removed the card. This change along with installing UPHClean seems to have made a huge difference in my case.