must be something simple

I am VERY computer illiterate. My computer was working very slowly so I tried a few tips to speed things up ( not from this site).
I did disk clean up, defrag (from windows xp) removed files, lots of desktop icons, programmes. I also did something to do with precatch and then msconf(?)
Everything was fine for a couple of days and, yes, things were quicker. Then yesterday I started to get a problem. The computer would not switch on. The power light was on but it did not make the powering up noises it usually does. The screen remained black and said No Signal like it does when switching off and then screen went black, switched off although the power was still on.
I did my usual technical things like switching on and off, unplugging etc pressing ctrl alt del f1 f12 f8 and various random combinations about 20 times and no luck. At one stage I did get a blue screen the horizontal lines, the blue changed to white then it died.
Eventually one last try as above and it came on normally smoothly and fairly quick. I thought it could be a virus so scanned (i have AVG)
I used all day with no problems and switched on and off all day to make sure all was ok. I found this site and tried to find out what was wrong. I read that the msconfig was not a good idea so chnged start up back to normal. I installed another defrag as recommended and c cleaner. This found about 300 errors but would not correct anything till I paid. I left it and uninstalled while I found out more.
Anyway confident the problem had somehow resolved itseld I switched on today and same problems, basically turning itself off before it even gets started. Lots of attempts turning on and off and unplugging then suddenly last attempt and everything works like a dream. Surely It can't be a coincidence and must be something to do with my messing about.

Totally confused and lokking for help
Goldie

 

CCleaner is (and always has been) 100% free to download and to use with full functionality. Uninstall whatever you downloaded as it may not be the correct program. Download and install this http://www.majorgeeks.com/CCleaner_Slim_No_Toolbar_d4191.html As to your issues with powering on; I do not think that it has anything to do with the tuning up you did in Windows (the disk clean up and defrag, etc). It sounds like the PC is not powering on at all. You're having power problems before Windows even starts to load (before the BIOS even starts to load from the sound of it) so I don't think they are related. Unplug the power cord from the PC. Open the case and make sure all the fans and heat sinks are clean. If there's lots of dust inside, visit your local PC shop and pick up some canned air and take the PC outside and blow all the dust and debris from in the case: clean all the fans, heatsinks, the motherboard, everything. Make sure all your fans are spinning freely and easily. Check the video card fan (if it has a fan) and make sure it is spinning free and easy. Then double check all the cable connections: both the motherboard connections and where the cables plug into your drives; make sure they are plugged in securely and completely; check the data cables and power cables. Remove your memory sticks, clean the contacts and the memory slots, then re-install your memory. Do the same with any and all cards (video card, modem, sound card, etc). Look at all the capacitors on the motherboard (these are the little cylinders about .5" tall with silver tops); they should all be perfectly flat on top. If any of them are even slightly bowed out or 'popped', or if any appear to be leaking a brown or off-white liquid, then you have a serious problem. If you have access to a 2nd power supply (maybe a friend has one?) install it and see if that fixes the problem. Yes, I know it's a lot to deal with, but this is all basic hardware troubleshooting and will help pinpoint the problem. Another thing you can try: disconnect the hard drive (both power and data cables) and see if the PC powers on to the POST screen; if so then we know the hard drive is bad. You can try the same thing with all the other drives (CD drives, floppy drives), and you can remove all the cards too (sound card, modem, if you have on-board video you can remove the video card too) and see if the PC powers on... be certain that you unplug the power cord from the PC each and every time you start removing or unplugging or connecting any devices in the case.
Good luck!

 

Thank you for your reply dlb.
I have downloaded and used cc cleaner. Thanks for that.
The rest I will leave till I have someone around to help me out with the dismantling. A bit scary for me!

Thanks again
Goldie