Hi Donna,
As Colin was eluding to, please use the Daily RF Health Report on Airwave as a tool to help us (all contributors) gain perspective on what may be occuring here.
The RF Health Report is Found in the reports section of Airwave and can be set up for a specific 'folder'. I would recommend setting up such that the APs within proximity to 'the unit' are in a seperate folder and the other APs that aren't causing issues(or don't appear to be) in another folder.
Please run the report against both folders, and we can then assess if there are significant discrepencies in areas such as:
Noise Floor, Channel changes within 24 hours, Power level changes within 24 hours, Errors on channels, Interferring devices detected and classified.
Worth a shot to further focus the investigation at layer 1...or higher depending on what the reports will show.