Beta 2's been absolutely stunning for me, but suddenly today my desktop icons were going nuts (er, flickering) whenever I changed tabs, or switched between an IE and a non-IE window.
I couldn't work out what was different at first, so figured it was probably an addin... after disabling all the add-ins it was still happening, though.
Then, I stumbled across an oddity in the menu bar: I had "Classic Menus" ticked, but they weren't showing. I had Links unticked. This seemed weird. More weird was that trying to untick "Classic Menus" didn't work...
Fixing it: Right-click any spot in the menu area, Untick "Lock the Toolbars", tick Links (this will show the menus too), then untick both links and Classic Menu". I locked the toolbars again afterwards. Menus Schmenus.
Yay! No more redraw!