CS4 component icon library bug.

I’ve been wondering why items in my library disappear occasionally – including the library buttons and column headers!

I’ve narrowed the problem down to a CS4 bug. Steps to reproduce bug:
1.Create a MovieClip
2. Select ‘Component Definition’
3. Add a parameter so that the component icon will become visible.
4. Select ‘Seek Bar Control Icon’ or ‘Buffering Control Icon’ as custom component icon.
5. Select ‘OK’
6. Watch the craziness ensue!