Agilent 1100 column oven strange behaviour in MassLynx 4.1

[bunnahabhain]

Dears
I have trouble with my Acilent 1100 column oven controlled by MassLynx 4.1 via GPIB.
The issue is, that I set "Left Temperature" and "Right temperature" both to 50.0 °C. When the method starts, the left Peltier elements begins to cool down after 0.1 min, while the right Peltier keeps the 50.0 °C.
What I tried so far: I wrote the method from scratch but it did not help.
I took the Column oven to a workstation running Chromeleon, where you can select "separate" or "combined" for the temperature control. I saw that it was set to "separate" and changed it to "combined", took the oven back to MassLynx but the issue persists. Taking it back to Chromeleon, I noticed that it was set back to "separate".
Is there any option to get it back to normal? It used to work for the six years that we own this system, this started only some weeks ago. There were no software updates, obviously, because neither the old MassLynx nor Windows XP are supported any more...
Thanks a lot
Jörg

[bunnahabhain]

This is a dual boot system using Chromeleon for PQ of the HPLC system exclusively, while MassLnyx is used for routine work.
The ColumnOven PQ sets 15.0 °C at time -1 min and the oven keeps this temperature at some strange point in its memory, surviving Reset and Power cycle of the instrument. So I set all temperature controls to "Off" in Chromeleon and rebooted to the MassLynx system and it behaves normally now.
This was a hard one to figure out...