Remote keypress results in multiple repeated actions

i’ll be honest, i have no idea what the problem is … my WDTV Media Player and Remote works fine.

Dunno, maybe try a plugging in a USB Keyboard and see if it does the same thing ?

or even via the WEB UI  or the Android App.

http://community.wd.com/t5/WD-TV-Live-Streaming/Remote-not-working-want-to-upgrade-firmware-for-apps-to-work/m-p/810703#M33711

If all the above work ok, then i guess it could be the remote ? … but, you need to test the other ways, before confirming that. 

(ps. no-one else in the house possibly playing a prank on you ? … because what you describe, is Very Odd Behaviour)