Cannot log to Proxmox GUI

[greg]

I'm running proxmox on debian 6.0.8 kernel 2.6.32-18-pve.
When I try to log into the GUI with the root password, it lets me in for about 2 seconds then asks for the password again:
<hostname>:8006/api2/json/cluster/resources 401 (permission denied - invalid ticket)
This is not the same behavior as when I give an incorrect password.
I suspect a hostname problem, but I can't sort it out.
My /etc/hosts contains the following line:
<ip> <shorthostname> <longhostname> pvelocalhost
The folder /etc/pve/nodes contains a folder name
The https certificates matches the hostname.
Any idea?
TIA
greg

 

[dietmar]

Is the system time correct?

 

[greg]

Thanks for your answer.
Yes, I checked the time it is correct. I even did a "dpkg-reconfigure tzdata" to be sure about the timezone.

 

[greg]

A new error message:

Parameter verification failed. (400)

POSTDATA: property is not defined in schema and the schema does not allow additional properties