I have this exact same problem. I'm running on 2.2 unrooted with no launcher. I got the smaller OTA 2.2 file.
there are times when i'll hit the home key from the browser, gtalk, or texting and the home screen will show up blank. takes about 5-10 secs for the OS to draw the icons and widgets. other times, the home screen icons and widgets will appear immediately but it will take 2-3 swipes before the OS responds and transitions.
Redraws like that happen. Try a different launcher and see if it's a problem with your phone or the stock launcher itself. ADW Launcher is a very good replacement and seems to be not only very customizable but very stable.