T-Mobile TP2, Data asks for username and domain
 

I've got my TP2 on t-mobile, and entered the data settings as described in a thread I found here. I'm running BigMax ROM. I've got the data settings entered and I can get on the internet and such, but every once and a while I get asked for username, password, and domain. I just hit ok, and it goes away and all is good. Any ideas on why it is popping up? Thanks.

Slevin