Lion cmd-tab doesn't bring the application windows to the foreground
When I switch between apps using Command-Tab the system brings the correct application to the foreground (as indicated by the menu bar) but the application's windows often remain in the background behind another app that is running in the same space.
e.g. if I have Mail and Preview running in Space 1 and Safari in Space 2, using command-tab to switch from Safari to Mail will often leave me seeing Mail's menus at the top of the screen, but looking at windows from open Preview documents. To get the correct windows to the foreground I often have to then either do a three-finger up swipe to get Mission Control and click on Mail, or use Command-Tab again and re-select Mail from the apps listed.
The App Switcher (Command-Tab) should bring the selected app AND its windows to the foreground, but this often doesn't happen - I say often because the behaviour is inconsistent, sometimes it works as it should, but often it doesn't.
Please, please don't reply to this query if all you have to offer is an alternative method of app switching - I know there are other ways to switch between apps but I've been using Command-Tab for years (and Macs for 20+ years) and I want to figure out how to fix this problem, not just work around it.
I'm working on an 11" MacBook Air with Lion 10.7.2
Thanks for your help!