With Ram being so cheap I purchased 8Gb kit for Mac Mini, since my other set had serious hardware faults after being replaced twice, and I went back to 4Gb kit and it developed this problem too.
Here is hoping for less bad luck with memory in the system. Purchased from Other World Computer (macsales.com)
Been having some very odd issues on the Mac Mini 4,1 system I have. It looks like the mouse started to play up, and oddly enough new batteries never changed the issue. Soon as I removed the ram, and put back factory memory. It all came good. It’s safe to say the 2 x 2gb modules I got have some issues. Think I will bin those, as they had no warranty.
It looks like Other World Computing (macsales.com) has some great prices. Might order from them some replacements.