[exim] Exim fills harddisk with error messages: Bad file des…

Our Mailserver (debian with exim4.50) unexpectedly rebooted. On booting
exim didn't start properly but filled the whole harddisk with
errormessages in the log-files (paniclog and mainlog)

2005-05-03 13:33:55 50 select() failures: Bad file descriptor

repeating all over again (about 3 GB! each).

This problem reoccurs on rebooting; on manually restarting exim4 via
init.d everything works fine until the next reboot.

I have no clue, where to look for configuration issues or what went
suddenly wrong. Any hints or help are well appreciated.

Thanks,
Johannes