I to am experiencing this same issue along with multiple other issues with my Ultra remote.
1. Many times my remote is unresponsive. It will not do anything. Thinking it is the batteries, I put fresh ones in, the remote works again for a short period of time then the remote returns to an unresponsive state. It is very frustrating. Sometimes unseating the batteries and re-seating them again does the trick, but not always. I bought a pack of new batteries and have rotated them through with the same issues.
2. The volume up bottom on occasion brings up the guide or pauses shows during playback instead of turning the volume up.