postfix problem SuSE 9.0?

Anyone having issues with postfix? I have to actually reboot the system to get mail working about every 4 or 5 days. Restarting postfix does not solve my problem. --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.561 / Virus Database: 353 - Release Date: 1/13/2004