RALPHEROO  Try setting the "Key to Show Search Channels Menu:" in the AcidSearch Preferences Options pane to a keypress combination other than nothing. Nothing seems to set Space and Return to show menu!  
(Version 0.7b4)

RALPHEROO  With AcidSearch 0.7b3 I just found a solution to the spacebar/return key bug.

In the AcidSearch Preferences -> Options pane there is there is an empty box for:-

Key to Show Search Channels Menu : [ ]

If this is set to nothing then Spacebar and Return bring up the window. If you set this to a key combination then it frees up Spacebar to actually type a space and the Return key submits the request rather than having to use the Enter key.

Hope this helps. I was just about to deinstall it. However when I first installed 0.7b3 this key press box was sort of hiding behing the Default Channel pulldown menu but after a while it appeared in its proper place at the bottom. Maybe it was reading corrupted settings from my previous 0.62 installation?

Ralph  
(Version 0.7b4)