any way to lock on to a network? X426

Alright, this is really starting to piss me off. I just got an X426 after years of nothing but Nokias (dropped my phone in a lake, took the cheapest thing ATT had at the time...big mistake, lol). It seems to work decently enough, except that it always wants to return to the ATT network, which has near zero signal in my house. I've already missed several very important calls from my GF because of this (like "my car broke, I'm in a BAD area of Detroit...). I know I can manually choose another network, such as the Cingular network that has awesome signal in the house. However, it seems like as soon as I flip the phone closed, or make a phone call, it reverts back to the ATT network. No matter how many times I manually choose Cingular, it eventually goes back. Is there any way that I can lock it on the Cingular network until I tell it otherwise?

This Samsung X426 constantly locks onto a non-functioning network (ATT), and no amount of manual reset to a working network (Cingular) can keep it there. Result: no service! ATT said it was Samsung's problem.... Any ideas?

yeah, I've got one. Dump the POS Samsung, and go back to Nokia like I should have done when I got this thing....unfortunetly funds don't allow for it at the moment, so I'm stuck for a few more months.