not ringing on incomming calls

[venaka]

I have searched this problem all over the web. Many HTC's with windows 6.1 and treo700wx's have had this same issue.
My phone will not ring for an incomming call .I will not even get a notification of a missed call on the log. I will only get notified if you leave a message on voicemail.
I called sprint and we were on the line forever, they didnt know what it was..So they sent me a new intrepid,,It worked for about a day or two..And it happened again today..Did a reset and it works again.
Another thing, If I go to update firmaware on the intrepid, i get an Error COde 4 under OMA DM CLIENT. "Firmware update could nopt be done at this time"..
I am worried that it will happen again.
Ca you guys tell me if when you go to update firmware you get an error.