I found a new bug in the IOS 12.2(55) on our c2960s where we had a high cpu usage and lot of traceback syslog messages.
Here is the info from the Cisco TAC about the problem:
C2960S switch getting the following message:
%SUPERVISOR-4-UNEXPECTED: rfd_idx = 56B hwptr 64D75AC queue 8 -Traceback= 12ECA7C 12EF254 12EF5DC 1382180 137C680 137C628 13821F0 1383128 137C730 184AA64 184AA3C 1848974
WS-C2960S running IOS earlier than 12.2(58)SE
Temporary workaround is reload, fix is in 12.2(58)SE
1. As a temporary workaround we can reload the switch.
2. For permanent solution please upgrade the switch to 12.2(58)SE.