well u can start by looking up support.microsoft.com and checking faq on problems faced for each OS . similarly , u can try support sites for dell , compaq , hp , ibm , gateway etc . Most have extensive problems and solutions and also have a good set of common problems and how you solve them . Else u can even get back issues of mags like pcq / dig / chip and use their q&a or troubleshooting columns . I think dig had most of their issues on a single cd itself and pcq gives their issues on a regular basis too .
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