When right-clicking many links in FF3/IW3, it quite often happens so that a random action is performed instead of opening the context menu (bug report).

One of the solutions work-arounds (suggested by Andre Pirard) is to slow-right-click, that is to hold the right mouse button down until the menu actually appears, then – and only then – release it. Or, you can even slow-right-click, move the pointer over the desired menu item, and then release – that will perform the desired action in a single long right click (instead of more common single right click with a following single left click.)

Alternative workaround (found at the bug report page): install the mouse gestures add-on, and restart firefox. Tested: works for me.

This bug/behaviour is otherwise unsolved.