Unfortunately, system accounting is not foolproof. Occasionally, a file becomes corrupted or lost. Some files can simply be ignored or restored from backup. However, certain files must be fixed to maintain the integrity of system accounting.
The wtmpx files seem to cause the most problems in the daily operation of system accounting. When the date is changed manually and the system is in multiuser mode, a set of date change records is written to the /var/adm/wtmpx file. The wtmpfix utility is designed to adjust the time stamps in the wtmp records when a date change is encountered. However, some combinations of date changes and reboots slip through the wtmpfix utility and cause the acctcon program to fail.