Today was the second time this happened to me in 2010. When I select an object in the canvas, the Options Bar (docked under the ribbon) seems to double itself between 2 to 4 times, then the ribbon refreshes and the duplicates disappear. A side-effect of this though is that whatever you selected in the canvas gets dragged vertically automatically. Very annoying and causes tons of issues as it happens with every object selection. This issue seems to happen on a laptop with a docking station and second monitor setup (mine was set as main monitor).
Yesterday I plugged the laptop into a projector and this seems to have made Revit freak out. So today I couldn’t work on my usual setup. Moving the Options Bar to the bottom puts an end to the madness, however I don’t like it docked there.
Thinking it’s a Ribbon issue, I decided to reset my QAT using the vbscript that Autodesk released earlier. That didn’t do it either, so I restored it back from the backup.
I finally got it to behave again by undocking (still logged into Windows) while Revit was open, then I closed Revit, re-docked (still logged in) and re-opened Revit. I had previously done a series of shut-downs, restarting without docking or attaching a second display etc. but none worked. Not sure what is going on but the above got the job done. I have not filed this with support yet.
EDIT: Click HERE to learn about suggestions from Autodesk Support. You might also want to take a look at “What Revit Wants” in this POST by Luke!
You can set an opening cut in hosted families to be transparent in 3D and/or Elevation. Above you can see the default settings. The reason I wasn't aware of it was possibly because material transparency is not respected in elevations. A common technique to get window glazing to show transparent in elevation is to use a 3D view oriented to an elevation, and thus the opening shows transparent due to the setting above. That's my excuse and I'm sticking to it!

