When I shutdown Windows XP the computer switches off and unless the computer is unplugged from the power point, after a few minutes the machine switches back on. A related problem is a second computer networked to the insomniac computer. If both are on, the second computer tells this one to connect to my ISP. On one occasion I was connected to my ISP for nearly four hours because the second computer switched itself on.

It is likely there is a setting in the BIOS setup of the computer which is causing the computer to switch on after being shutdown. The BIOS contains settings which are written directly back to the motherboard and contain important settings about computer hardware (e.g., hard drives). Of particular relevance to your case, are the power management BIOS settings. To enter the BIOS setup, restart your computer and a message should be displayed along the lines of ‘Press DEL to enter setup’. When this message is displayed, press the key which is requested (in this case, DEL) and the BIOS setup should appear. Look through the BIOS setup for the power management settings (the exact title will differ depending on your motherboard). You will probably find some settings similar to ‘Wake on LAN’, ‘Auto Power On’, or ‘Remote Wake Up’. Make sure these settings (and any others which look as if they could attribute to the problem) are disabled. However, if you are not sure about the meaning of a setting do not alter the setting. Should you mistakenly change a setting, exit the BIOS setup and DO NOT save the changes; then reattempt the procedure. Once you are satisfied with the settings, exit the BIOS setup and save changes. The problem should no long persist.

In relation to your other issue, it is convenient to have the main computer dial-up the internet at the request of the other machine, as this saves the hassle of having to dial-up the internet on the main computer when you wish to access it on the other machine. However, if you would like to disable this feature, open Internet Explorer and go to the ‘Tools’ menu > ‘Internet Options’¦’. In the window that appears, click the ‘Connections’ tab. Under ‘Dial-up and Virtual Private Network settings’, in the list of connections select your internet connection and click to enable ‘Never dial a connection’. Click OK to save changes and close the Window.