Spaces, Finder and applications switching bug

At first I must say Spaces and Finder was no so good in 10.5 too. Probably for the way I use them - Finder is assigned only to one space (the first one) and the way Mac OS X is implemented the Desktop - its just another Finder window. But in 10.5 that was just minor bugs as not showing selection box on desktop on another space as the one which to Finder was assigned.

But on on 10.6 with same scenario (Finder assigned to space 1 some application as Adium, Skype on every space, Firefox, NetNewsWire on space 2...) when I want to switch just for example from Firefox (space 2) to Finder (space 1) sometimes I end up switched to Adium (or Skype). Finder is showed but another application is in focus. With sometimes I mean very specific circumstances - Finder must be assigned to one space, on that space must be just one application which is assigned to every space showed (if there is another one switching works fine). Problem is just with Finder. Another applications assigned to space 1 works fine.

Is there any workaround for this bug? Have anyone same problem? Is it problem with upgrade from 10.5, can clean install help?