Are you using static WEP or something else? Also, does this happen on all clients at the same time, or all APs at the same time, or neither? How frequently do you see this issue? Finally, you might want to look at this field notice. It doesn't mention the issue with the 1231, but it's worth noting (sounded similar, but I don't think this is your issue). Also, what are your handheld clients?
Transferring Crash file from standby: Login to the Active WLC in HA.
From CLI: (Cisco Controller) >transfer upload datatype crash (Cisco
Controller) >transfer upload filename (Cisco
Controller) >transfer upload mode tftp (Cisco Controller) >transfer
This is the start of a display filter cross reference between Wireshark
and OmniPeek. The 1st installment is a table of advanced filters. More
filters will be added as time allows. It is a living doc, so check back
for changes every so often Please feel f...