I am having exactly the same issue with Right click flutter in Retail WoW. The issue has only started recently. I thought it was my mouse and have replaced it since it started. I have had the same flutter with two new mice using up to date firm ware and software . Both a Naga Trinity and Corsair Scimitar had the same issue. I took an old USB two button mouse from another PC and the problem persisted. I have disabled my addons and still had the issue. I have also closed out all start up programs to screen for conflicts with no fix.
Fatherfrog,
There are a load of things that can cause this. Usually it’s just going to be addons if it happens on two different mice. Unfortunately, disabling them isn’t enough. Can you try uninstalling any addon managers (Twitch, Raider.io, tukui client, etc) and resetting your UI?
If you’re still having problems after that - does it happen randomly, or in a specific location in the WoW screen?