Test your RAM using Memtest 86+.
Download and run the Memtest86+ programme from
HERE.
Download either the ISO version, or if you have a floppy drive, download the floppy version.
The ISO version needs to be burned to a cd as an image. Your burning software will tell you how to burn an image file.
Once done, with either the Memtest86+ cd in your cd drive, or the Metest86+ Floppy in your floppy drive, reboot your system.
Let the programme run for at least seven passes. If Memtest86+ gives you errors, then it`s likely your ram is bad. However, please be aware that some faulty ram can pass Memtes86+. Check each stick of ram individually, then together.
Please note: If Memtest86+ gives you errors, your ram is more than likely bad. However, please also be aware, that some faulty ram can pass Memtest86+ or any other software memory tester come to that.
If your ram checks out ok, then I suggest trying a Windows repair as per the instructions
HERE.