Returning to auto network selection problem

[Guest c-shadow]

A couple of days ago I finally flashed my old GSM HTC Hero to Modaco 3.2 :(

Was on rooted stock 2.73.405.5 before. Even without a wipe everything worked fine. Except for one problem: I cannot "lock" the hero to a specific network. At home I have a weak signal of my home network (tele2), but they have a national romaing with t-mobile so I always manually selected that network (have full signal there). After flashing MCR 3.2 and selecting a network, in a minue or two the phone shows this message

The connection breaks for a couple of seconds and it switches back to home network. An it also tends to do that in the other way, breaking a connection for a moment.

I flashed the latest radio (63.18.55.06JU_6.35.09.26) but it behaves the same. Tried fiddling with all options I could find (data roaming,...), and found out that there isn't any more "Use only 2G networks", or something like that, don't know if this is significant or not...

Help, how do I select the specific network and make it stick?

Edited June 5, 2010 by c-shadow