Then you have a bad stick of RAM,if this is new bought RAM I would return it as faulty.Do not put the RAM back into your computer.

__________________
It is all in the hardware..........................................
Sources:
http://www.microsoft.com/en/gb/default.aspx
http://www.seagate.com/www/en-us/Home/
http://www.petri.co.il/index.htm

PCHF Rules Scan Computer for Driver Updates Pre-Work

i have 4x1gb .... how to find which 2 of them are good

Remove all RAM,put one in and run mem test for a little while.Then take it out and put another stick in do this for each RAM in turn.Individal sticks is the key not all at once.

__________________
It is all in the hardware..........................................
Sources:
http://www.microsoft.com/en/gb/default.aspx
http://www.seagate.com/www/en-us/Home/
http://www.petri.co.il/index.htm

PCHF Rules Scan Computer for Driver Updates Pre-Work

One of the ram slots on the motherboard could be faulty. You may need to replace the motherboard.

There is another thing that can cause your problems which is your CPU, it has a known problem that the latest BIOS update from Gigabyte fixes.

The easiest way to update the BIOS is to install @BIOS from the CD that came with your motherboard. This will allow you to upgrade the BIOS from within windows. I recommend you do this with only 1 stick of ram in, due to the problems you have had so far. Also it may be a good idea to restore defaults in BIOS before trying the update as it may make the system a little more stable.

When you first run the tool - backup your current BIOS. After that has completed then click update BIOS. Refer to your motherboard manual for detailed information on how to do this.

Post back if you have updated your BIOS and the problem still occurs.

I am running the latest F5 bios...
I am afraid to run the @bios tool because if my system crash in the middle of the update i may loose the motherboard ....
I will re flush the bios with 1gig only and see what happend

I did test all the slots on the motherboard with the same 1 stick of ram and was fine...all succeeded

Newegg.com - Crucial Ballistix 1GB 240-Pin DDR2 SDRAM DDR2 1066 (PC2 8500) Desktop Memory - Desktop Memory

I think the customers reviews on this page answer all my questions...actually the first review explain exactly what my pc is doing
Thank you all for trying to solve my problems

No problem - will mark as resolved - hope you have better luck when you get new ram.