Unable to create exclude_field routine

I receive the following message every time I send a messagge to a mhonarc
alias. If I run mhonarc -editidx the error message is give, but if I
remove the .mhonarc.db file and rerun mhonarc -editidx no error message is
given and .mhonarc.db is recreated.

Could someone tell me why the .mhonarc.db files were corrupted?

Thanks,
Riccardo


Reading database ...
Reading resource file:
/opt/petra/data/VirtualDomains/cinsedo.it/././www/conf/allevidenze.rc ...
Requiring content filter libraries ...
        mhexternal.pl
        mhtxthtml.pl
        mhtxtplain.pl
        mhtxtsetext.pl
Requiring charset filter libraries ...
        iso8859.pl
ERROR: Unable to create exclude_field routine:
/^*/: regexp *+ operand could be empty at (eval 82) line 11.