Memtest86.com - Memory Diagnostic

You can download from the above link.
You will need either Nero or some other burning software to make the bootable CD.

Download the ISO image for creating bootable CD (Windows - zip) and unzip the contents to your desktop. It will be what is known as an ISO image file.
Open the burning software and click to burn an image file. the program will need to be pointed to the desktop and it will show the ISO file open the ISO and the burning software will auto produce a bootable CD with memtest86 application installed.
1) make sure the CD/DVD drive is set for first boot from within the BIOS (set-up)
2)Insert th CD in the CD/DVD drive and restart the computer.
3) when prompted to boot to CD, hit enter.
4) follow the prompts to start the program and let it run for minimum of 12 hours or more...unless errors are shown almost immediately .

Any errors means the memory stick is bad and will need to be removed/replaced.