Hardware problems are quite difficult to tackle, worse if under Windows. There was once when installing a software, I accidentally inserted the Audio hardware diskette. Thinking it was harmless, I went on, thinking I can always "undo" everything again. How wrong was I. The next moment I restarted Windows, I got the blue screen of death. Yeah, Windows is very nasty when it comes to hardware.
Find The Culprit
Always calm down. Try to solve the problem yourself before resolving to formatting or sending to your computer dealer. First, know what's happening and the cause of it. In my case, the installation must have overwrite my old setting and replaced the wrong file. There must be a reason why Windows is acting improperly.
Logging Back On
First, try to log back on. If you can't log into Windows, don't panic. Restart the computer. When the text "Starting Windows 98..." appears, press F8. A menu will appear. Choose "Safe Mode" to continue. Safe mode will take some time to load. When you are in Windows, go to Control Panel, System. Click on the Device Manager tab. Find the faulty hardware driver and delete it. Open autoexec.bat and config.sys (both are hidden files in your root directory) with notepad. If the hardware is a CD-ROM or sound card, it will probably write add some lines. Check whether there are backup file (autoexec.bak, autoexec.b~k e.g.) since most installation will back up the 2 important files. If there is, simply replace them with the backup files. If there isn't, put "REM " in front of every line that loads the hardware.
When you restart, your computer is probably ok, since you have deleted all instances of the hardware drivers. But the hardware isn't functioning. re-install the hardware drivers, restart and you're done! If the problem persists, your probably have a system conflict go to the next page for more.