Hope people can give me advice on this problem because it is absolutely puzzling me and I'm just about ready to throw my laptop out of the window.

Recently i bought a new 1GB Ram card for my laptop because both Ram card slots on have a 256mb card i had to take 1 out and then put the new 1GB card in, so i upgraded to 1280mb Ram from 512mb. After a couple of days my system shut down automatically and restarted i thought nothing of it at the time and nothing else happened for about 4-5 days, then yesterday and today it has been constantly restarting yesterday about 5 times in 2 hours and then today about once every 5 minutes for the last hour. I think i my have a temp or power supply problem but not sure, I have been monitoring temps of the CPU and HDD and the they are higher than what they were before i added the new card there is not so much difference in the CPU about 2C the CPU temp is currently 45C and doesn't go higher than 50C but the HDD temp has skyrocketed to between 45-50C from about 38-40C so i am thinking the problem is temp and the power supply. If anyone has any thoughts i would greatly appreciate them.
I will post my system spec on my profile as well.

Reseat your RAM and make sure it's fully seated. Run Memtest86.

Ok i have reseated the RAM and have double checked that it is fully seated and also Ran Memtest86 which showed no errors in 5 passes not had a restart yet though so will see if anything happens.
I will try to run a virus scan and spyware scan as well see if that finds anything.

I finished my virus and spyware scan using Windows Defender i scanned every single file and bit of data on my system took 2h 30mins and it found 6 files all High threats hidden as Win32 files so removed them and reported them to Microsoft when prompted by Windows Defender. Don't know if that will fix the restart problem i'll see.

Also thanks for your input Zenosincks

I'm not sure about 2.5" HDDs (though, I doubt there's a difference), but the standard 3.5" HDD is fine at 45C as far as I'm aware. It's getting toward the toasty side but it should be fully operational.

Why not try taking the new module out and putting the old module back for a day or two and see if the issue clears up?

I did change back to the old RAM card temps dropped back to what they were. And have had no restarts yet.
Thinking about it now this may just have been a bit of stupidity on my part, when i was going to put this new RAM card in i knew my motherboard could run upto 2GB of RAM but i didn't take into account the power it would take to power the card and the obvious temp increase it would cause.
Also the techies at PC World where i bought it from didn't say anything or warn me about that at all.
I'll have to find a way of cooling the system better. And maybe see if i can get a better battery to provide more power for the system?

I still have the restarts not had as many as before after i had changed back to my old RAM card but still have a least 1 restart a day

I've read some other peoples threads about random restarts and 1 had sent the laptop back and when it came back all they did was clean the system and it has worked fine since.

So I'm going to try and clean with some of that compressed air to see if that works.

Good idea...

I have cleaned the laptop monitored the temps they have gone lower by about 3C but I have still had the restarts, so I'm back to square 1 still having problems and not sure what else to try.
The only things i haven't tested is my power supply (battery), hard drive, CPU and maybe my motherboard but i wouldn't know how to test the motherboard or CPU properly.
I thinking maybe the RAM card I put in may have damaged something, any other advice would be helpful.

I have checked my hard drive using Speedfan and that shows that everything is working properly all rated Good or Very Good, also the only thing that needs doing with my battery is that it needs re-calibrating, but still haven't found the problem. And still having the restarts.
I also rolled back my graphics drivers which was suggested on other threads titled "Random Restarts".

As a last resort before arranging for it to be sent to a repair shop, I'm going to remove all casing and check that all the wires are connected properly and check that all hardware is connected properly as well.

Any other suggestions are still welcome.

I found out the Hard Drive or the connector to the motherboard is faulty. I only picked my laptop up and it restarted earlier.
I took the HDD out and put a Ubuntu bootable disk in to try that and it was working fine when i moved it and had running for a bit.

Also if I find this is a connector problem between the HDD and Motherboard then would it be possible to use an external hard drive as a boot device?
Or are External Hard Drives just used for the extra storage space?

Assuming you're using the USB interface with the external drive, you can, however, your BIOS has to support booting off USB. I wouldn't recommend this as a permanent replacement...

I would bet on the HDD being defective over the motherboard. Try replacing it and see what happens.

I was going to use a USB connection but I'm 90% sure my BIOS doesn't support USB booting so using the external hard drive is out of the question.

Will have to try replacing HDD tomorrow, 9:15pm here currently and have no other SATA HDD in house.

This is not for the thread but when will the GMT time be put forward an hour because it's not Daylight Saving Time here any more we're back to standard time. Not a massive problem just wondered, don't know if people in the US put there clocks forwards or backwards.

This year, daylight time began on 3/9 and ends 11/2 for the US .

In the UK it is 31st March till 26th October this Year, us being further up North.

Also thanks for posts over last few days, will post back to say if problem is sorted out with new HDD.
With all the tests I've done this would sort anyones Restart problems out.

You're welcome, I just wish I had more to contribute .

Bought a new 120GB HDD today £45 ($90) but -£30 (-$60) because i took the RAM card i had bought and returned because that is what had caused the problems so the HDD only cost £15 ($30).
Seems alright now just finished installing Windows. Installing my device drivers now to get Internet, Video and Sound back.