#8 vacation stop working randomly with error 1

[Anonymous]

Vacation 1.2.7.0 on RHEL5.4 64 bits sometimes stop working.

Prior to the error, (after days of correct behavior) this message appears in maillog:
vacation[4741]: vacation: .vacation.db: Success

after this message, all mails will trigger the above message an this error:

Command died with status 1: "/usr/bin/vacation -a blabla@domain shortblabla"

What could trig the first message in the log ? The 7 days limit (default value) wasn't reached, I cannot reproduce the bug.

Thanks