I am using Ubuntu 11.10 x64. Ubuntu freezes when I pressed minimize button when in maximized windows but minimize button works well in non-maximized(restored) windows. Also, the unity sidebar doesn't shows occasionally when hovered in left.
i encounter this problem my self on both of my computer, the problems occur when i upgrade the motherboard of both of the PCs. Both system are not identical, one is AMD pc and one is Intel pc. So it confuses me why the problem occurs cause im not doing a clean install, i just use the same previous hardisk directly on the systems. I just find the solutions yesterday when i use live cd on the system, it seems that the configurations are messed up because of maybe the previous configuration of ubuntu. So this is the solutions i did:
Solution 1. Just create a new administator / user account. Your new account should work as it should. No unity freezing when minimize from a maximized window.
Solution 2. Use either gnome shell or live cd and browse to ur directory using root.
browse to your home directory: please enable hidden files from View option first
delete .compiz-1 folder delete .compiz-1 & dconf inside .config folder delete .gconf folder (or maybe just the compiz folder inside apps inside the folder.. im not sure cause i just delete .gconf folder directly)
lastly restart Ubuntu, and log in.
I hope this will solved your problem
--William, Ubuntu User Malaysia