Ok,
PC Switches itself off when booting up, Temp 70 Degrees Celsius.
After when i press restart, or if a program requires restart after installation, the computer boots up to a certain point and switches itself off. This is starting to get really annoying, as i have to wait till the PC cools down for a few minutes before switching it back on.

I had this problem for around 4-5 months now and now im starting to get really irritated.

Also Sometimes my Hard drive makes really freaky clicking sounds, its probably going to die soon.... Even though Belarc says its healthy.

I have Opened the side of my case to see if that keeps it cooler, it works... but not well.

My case is small and compact and everything is squashed together... The Manufacturer is Evesham, However you can only get this specific computer from my dads work as he has it on loan and i cant find it on any other site

System Specs can be found in my Sig.

So i was hoping if anyone knows what is causing this problem, so i can fix it and hopefully get my comp back to the way it used to be

EDIT: Any Questions Please ask

1.Probably you have a problem with processor (90%).
2. Run a benchmark test with SpeedFan (will check the temperature ,too)
3.Check for malware or computer viruses (nod32 antivirus)

I has similar problems last year, i was with computer at the shop to return , but it was a virus .Hope helps.

Have you checked your BIOS settings for shutting down computer if the CPU reaches certain temperature?
You said that everything is squashed together, well, you might have too much heat build up. If you can, try to reorganize the cables and blow the dust out of it. Dust is the number one cause for overheating. Do you have a exhaust fan for cooling ambient temperature inside of the case? Having just the fan from the power supply is not enough.

How would i go to the BIOS?
Ill try and get all the dust... would a vacuum cleaner be alright, or would that damage the PC?  
No, no exhaust fan.

When you boot the computer it should say something like "Press F4 to enter Setup"..

I've cleaned with a vacuum and seems to be alright.

Do you have place for a fan? If you do, I suggest you buy and install one..

Ok,
1) Checked the BIOS, all seems fine. Temperature shut off thingy disabled.
2) Cleaned Computers insides, now dust free... also checked for any lose wiring and made sure every single wire was tightly secure in its rightful place.
3) No, no place for the fan as the case is too small.

I'm now currently checking for Virii and spyware that may be lurking in my hard drive. So hopefuly when this is all sorted my comp will be clean as a whistle and will work properly

Thanks for your help guys, and will keep you posted if any changes occur...

Are you over-clocking it?
You may need to buy a new case/computer with a fan!

multirama has nice cases in low prices... and with many places to put fans... mine is around 50 C with 3 fans (1 not working due to: i need an adaptor)

No Im not overclocking it...my dad wont let me as its a work computer and hes still paying for it.
Hopefully by the end of this month the computer will be fully ours and then i can do whatever i want to it.
So im going to buy a new larger case and new fans to keep it cool.
Ive also decided to buy a new 500gb HDD too

Also i found a rootkit on my hard drive, thats probably whats causing the trouble, lucky enough avast got it.
and a bunch of cookies, found by Spybot S&D

Other than that, its clean.

I'll cyberscrub the HDD tomorrow, as i have all day to do it and the program takes a hell of a long time to finish.

Anywaaay, thanks for your help guys, really appreciate it

Other than that one more question:
whats the best security programs out, that is FREE?

Currently i have Avast, PC Tools Firewall, Threatfire and Spybot S&D.

Lavasoft Adaware
(and maybe try Kaspersky Antivirus/Firewall, but it`s only  30 day trial)

I suggest you use ZoneAlarm Free firewall as your firewall

Thankyou Breakfastclub and Legace  

Spyware Terminator, a-squared 3.5 (beta) Free, Avira Antivir, Panda anti-rootkit (at download.com), HighJachThis. A few of the must a pc needs

to breakfast: ad-aware is full of false positives, it's detecting abilities sucks hardly, and the whole product is a must to those who don't know anything better than it. i suggest u use Spyware Terminator or another freeware anti-spyware (don't start from the low life ones)