I had this problem before upgrading to 6.3.3, still having. It occurred on two new computers running Windows 7, while older XP computers were fine. My workaround has been maximizing before going to II, as Sandeep suggested I recently bought another computer to replace an XP computer and this one does not do it. All 3 running same version of acrobat Reader and Windows 7. Someone might be able to look at all 3 and see what the difference is, if interested.
