Are the AP's loosing connectivity? The error shows failed authentication of a users to the specified radius server. Post the VALIDITY IDENTITY MODE error you are seeing. If the AP's are getting that error, do you have validate AP to AAA enabled?
We seem to be getting the same error msge too. It reads something like this
When IAS logging is turned on, the log file jumps in size very quickly, approx 8MB a minute, filled with the same message over and over: ,,IAS,,4128,wireless lan controller,25,311 1 30354085,4132,Secured password (EAP-MSCHAP v2),4127,11,8100,1,4130,0x4947454E2E4C4F43414C2F2142657468657364612F55736572732F4C6F6773646F6E2C2044656C656E61,4294967206,0,4294967207,1,4108,,4116,0,4155,1,4154,Use Windows authentication for all users,4129,,4149,authenticate wireless lan users with PEAP,4136,2,4142,0..."