You running on AT&T or T-Mobile? I run the 9530 on AT&T and have this problem all the time. Mendez777 idea somethings help. Sometimes I go to the same setting and change Network Technology to 1XEV, let it set up and then change it back to GSM/UMTS and 2G only. That sometimes works.
I find I pop in and out of EDGE/edge without cause when opening different applications. If I let the phone sit for awhile it seems to "heal" itself, but it is frustrating. As long as I can get EDGE back I am a happy camper. I am thinking I am going to have to live with this until they come out with the "Storm" variant on AT&T.