Yep , there is something wrong in 7.3 .
When you enable the auditing in PPES, it generates a ppes_audit.log.
When the PPES service/daemon is stopped and started , the ppes_audit.log is renamed in ppes_audit1.log , and a new ppes_audit.log is created.
With 7.3 mr1 , at least , the file creation is not functionning , and the old ppes_audit.log is appended instead of renaming it, which cause the problem for sessionizer and the cognos parser.