Hi TK,
First of all, there is no point in changing parts until you have figured out what is wrong.
We do this by a process of elimination.
-Smoking does not affect your pc.
-If you can see the screen, the monitor is working.
-If you can see windows the power supply is working.
-Check all fans are working, if not replace.
If fans are working, pc + processor are kept cool.
Also check inside is clean and free from dust and fluff and also keep pc where air gets all around it and not underneath a closed desk.
Causes of pc shut down.
-Pc or cpu overheating (fans not working)
-Virus (run antivirus, keep firewall on, empty r/bin).
- Power supply blown. Won't startup again then.
Power supply is very dangerous, do not replace it yourself, get an IT tech to do it.
Is your anti virus up to date and running?
Is your windows firewall on?
Do you have more than one virus software running?, if so remove one completely.
Have you added something to your pc, inside or out that's in conflict with your pc.
Run antivirus and see if it finds viruses.
Hope this helps.
Anne, October 2008