Phone won't answer or no audio on connect?

[yachtspecco]

I never had this problem until the most recent Sprint Rom update. After a while during the day the phone simply won't receive calls or if I try to call out it says connected but do not hear a ring sound or audio. I have to soft reset to restore operation and then make a call.
Is this a common problem? Anyone else have this and found a solution? Is it likely that the rom update didn't completely "take" and I need to reload it or is it most likely a hardware issue that will require replacing the phone?
Thanks in advance. This website is a lifesaver!!!!!!
John