I got this weired message while trying to save a configuration :

#wr mem
Building configuration...
% Warning: Saving this config to nvram may corrupt any network management or security files stored at the end of nvram.
Continue? [no]: no
% Configuration buffer full, can't add command:
************************************************************************

Looks scary at first, but normally it should be solved with a single command :

# configure terminal
(config-ter)# service compress-config
(config-ter)# end
# write mem

I guess that there are little chances the issue remains after that, but if so, well, you may be in trouble…