The only successful solution in three such cases was a complete OS restore using the .iso The .ISO that should be used should be 6.0.2 or greater to avoid any fall-out with the expired trusted cert in previous versions - pre November 30th 2009. This issue has been evident within three different cases. In all case's all the standard troubleshooting and resolution suggestions usually associated with file system corruption proved unsuccessful.
However in a case this steps provided a good solution.
Make sure the time is well set in the appliances.
Run the clear command to delete the data.
reboot the appliance.
This is an output example we got after troubleshooting steps:
login as: root root@xxx: Your account will expire in 5 days. Last login: Wed Sep 1 02:13:57 2010 from domain.net.xxx.xxx.xxx'spassword