What type environment are they in, they could be channel hopping if they are in a busy wireless environment (office complex, or apartment).
Are the channels set to "auto" or manually set.
What wireless networks are nearby?
Metageek used to have free tool "Inssider" there is also another at ampedwireless.com look for wifi analytics. That will allow you to do a basic site survey to see where and what channel to place the APs.
1.1.0.4 is the latest firmware for that device, what version is on yours?
http://software.cisco.com/download/release.html?mdfid=284798654&softwareid=282463166&release=1.1.0.4
Are there any log messages in the device? Logging is turned on in admin-->logging --> enable persistance. You can also set up a remote syslog server to gather the messages.
You can gather the diagnostics by going to administration-->support info--> download
The best way to open a case is to go to the cisco site, support-->open a case
You will need a CCO ID (register in the upper right), once you get the case number, Call in http://www.cisco.com/c/en/us/support/web/tsd-cisco-small-business-support-center-contacts.html (866-606-1866 in the US and canada) and follow the menus for existing case. That will connect you directly to an engineer who can help you.