It seems to me to be cookie related.
08/09/2003 19:18:14: (I) Opened session for 'CN=System Administrator/O=System' '
127.0.0.1' (SYSTEM - pmaSystem)
08/09/2003 19:18:14: (D) 6: 14-F7837D8B08-F7837F8503 [POST /system/admin.pma/$Lo
gin?SavePage HTTP/1.1] (CN=System Administrator/O=System - pmaSession)
08/09/2003 19:18:14: (I) No Anonymous access is allowed to '/system/admin.pma/Lo
g?OpenPage'. Requesting login (Anonymous [127.0.0.1] - HTTPRequestManager (80))
08/09/2003 19:18:14: (D) 7: 15-F7837D8B08-F7837F859F [GET /system/admin.pma/Log?
OpenPage HTTP/1.1] (Anonymous - pmaSession)
You can see the different session IDs between the two requests:
14-F7837D8B08-F7837F8503 (from the POST)
15-F7837D8B08-F7837F859F (from the second GET)
When Puakma receives a request from a client, it checks the session cookie sent by the browser against the list of server sessions, if the session does not exist, a new session is created and a new session ID allocated. It is possible that your firewall software is somehow interfering with the process (maybe stripping out the cookie on a POST?). Try turning the firewall off and see if that makes a difference.
I did a quick Google search and it seems there may be some issues with ZoneAlarm and cookies: