ORA-01801: date format is too long for internal buffer

Our application is running 24X7 in a customer place and they are facing this particular error at times. Then they need to restart the Database to resolve this error. In Application programmatically absolutely no issues regarding date formats.
DB version is 9.2.0.5.
Can anybody give inputs what could be the reason and what needs to be done.

Regards
Srini.