Multiple abilities being used when clicking mouse buttons

Hi all,

I'm hoping I can get some help with this issue. I have abilities bound to my mouse buttons 1-12 (MMO mouse buttons) however every time I use an ability it casts others simultaneously. For example, when pressing 1 on the mouse, often 2 and 3 are also used simultaneously. This wasn't too bad during the campaign but now running maps is getting me killed a lot. I was wondering if anyone else had experienced this and what you did to solve it.

Thanks!