If someone want test ram using memtest on install disk, he will get error on test 7. [Random number sequence] It’s somethink like ubuntu 12.10. https://bugs.launchpad.net/ubuntu/+source/memtest86+/+bug/1071209 Please change memtest. 
I can verify this is a known issue with memtest+ 4.20, I had the same errors using the official 4.20 iso from Memtest’s website. The next ISO release should work fine as it will use Memtest 5.01 or higher.