[Solved] Panel login error (Error 503); reboot needed after each login

[woggel]

Hi all,

I have a very serious and anoying problem.

Whenever I log into the panel with any account all works fine.
After logging out and try to log in again; straigth away or at a later stage I get an

Quote:Error 503!

/index.php
Service Unavailable!

To be able to log in the panal again I have to restart the server.
All the hosted websites are running fine.

Does anybody know what this could be or how to solve this?

Sincerely yours
Woggel

EDIT:
No problem of ispCP Omega. One of my HDD was getting sick of working and switched into read-only mode to prevent more data loss. Therefore ispCP Omega could not write an files to the partition and this caused the error.