Create CD from the image by using ImgBurn: http://www.filehippo.com/download_imgburn
Then boot your faulty PC from that CD. Wait until a short menu appears, then highlight "ATA Only" and press <Enter>. Test the drive using the Long/Extended test.
If the drive is healthy, (test successful), test the RAM with Memtest86. The CD Image is here (Pre-Compiled Bootable ISO (.zip): http://www.memtest.org/#downiso
Unzip the ISO file and again use ImgBurn to create a CD from it, then boot your PC from it.
The memory test will run automatically, and keeps running until you press <Esc>
Any errors usually appear within the first five passes, so no need to run it beyond that.
If you have more than 1 RAM stick installed, test each one separately by removing the others, then you'll know which stick, if any, has errors.