I fitted a new 3 button mouse to my computer running Windows NT 4. When I try to log on to the internet (using my dial-up connection) an ‘Error 633′ message appears. It seems that the mouse is conflicting with the modem port. Next time I turned the machine on there was a noise, as if the keyboard was not plugged in. The keyboard was plugged in. Then I tried the keyboard on my other machine, running Windows 95, with no problems. After reconnecting the keyboard to my NT machine it no longer makes the chirping sound, instead when I reach the logon screen there is no response at all. All I can do is switch off. Any suggestions?

The main priority here is to get your computer to a state where it will work. Firstly, disconnect all devices from your computer (e.g., modem) except your keyboard and mouse. Should the problem continue, unplug your mouse. If your computer now recognises the keyboard, and allows you to logon, the problem seems to be your mouse - which caused all the other problems as well. In this case, you may wish to consider finding another mouse for the time being or buying a new one. I can’t say for sure what is the problem with the current 3 button mouse, but as you said, chances are it is a conflict of sorts. However, if after unplugging all devices, except the keyboard, Windows still does not recognise your keyboard (and thus will not allow you to logon) we will need to find out whether this is a computer-wide problem, or just Windows. The best way to do this is by using a boot disk to boot the computer to a DOS command prompt. If the computer will allow you to type in commands at the command prompt, it is a Windows problem. If it doesn’t recognise your input, it is a computer-wide problem (in which case you are in real strife). You can create a boot disk on your other computer by going to the ‘Start’ menu > ‘Settings’ > ‘Control Panel’ and open the ‘Add/Remove Programs’ control panel. Click the ‘Startup Disk’ tab and click ‘Create Disk’. Follow the prompts to create the boot disk. Once you have done this, switch off your NT 4 computer, place the disk into the disk drive, and turn it on. The computer should boot to the DOS command prompt. Try typing something. If you can type at the prompt, the problem is Windows. Unfortunately, as Windows NT 4 does not have a ‘Safe Mode’ boot option I am unsure how we could solve this problem short of reinstalling Windows. You may wish to try connecting another keyboard before taking the drastic action of reinstalling Windows. On the other hand, if you cannot type at the DOS prompt then you seem to have a rather serious hardware related problem. This would be very difficult to solve by correspondence, so you should consult a computer technician who can provide further guidance.