tss.. fix virusses, or worm filled computers; fix a broken harddrive!..
Seldomly I get the opportunity to advise buying a new pc!
They all expect me to fix it!
The best fix ever was just adding some RAM.
The worst ... I'll not even mention!
But it is close to losing 3 days of your time, to in the end fry the computer totally,because it was never maintained or taken care of.
If you're good with people,or can use your mounth,it's easy to make people understand it's their fault.
But many ask you to fix their pc's for free,when it's almost unfixable, and if anything happens,and you return it in a worse state then before they will want to sue you...
Like that time when I received a broken pc,powered it up, and the processor literally exploded! Turned out the guy had overclocked it above it's limits and wanted me to fix it;but by then the damage was already done!