Yyouask, I have exactly the same phone as you, bronze US version that I bought from ebay unlocked. Sorry to be the bearer of bad news, but for some reason my phone is fine now. It just sorted itself out. Did you create a new APN shown below?
Name: Virgin
APN: gotovirginmobile.uk
Proxy: 193.30.166.003
Port: 8080
Username: user
Password: <not set>
Server: <not set>
MMSC:
http://mms.virginmobile.co.uk:8002
MMS proxy: 193.30.166.002
MMS port:8080
MCC: 234
MNC: 30
APN type: default
The only things I think may have changed on my phone is I now use taskkiller(android Market). Other than this I'm not sure, you could always try Virgin