No bug ID that I know of, but here is an email address of Cisco support person that is working the problem. rmarg@cisco.com. Long and short is they hope to have a fix in the next WLC version.
This is a known issue that Cisco and Intel are currently working. Many users have completely disabled 802.11n capability until the issue is resolved. Since I only have a few 1142's at one site, I have let the clients set their laptops to 802.11a on...