Web Search Pro 2.8 by accident contained quite a big bug which I apparently forgot to fix before releasing it. The new way keyboard shortcuts for Search Engines and Groups are created did not correctly get a modifier (ALT/SHIFT) assigned to them. This caused them not to work as expected, and more seriously caused them to work when you least expected it.
Sorry all for the inconvenience, and thanks natri23 for being the first to notice and report it to me.