cloud service web role did not get request

Hi Team,

we have an application host in web role in a cloud service, 

sometimes it keeps loading when clicking a button in GUI and got no response till our GUI timeout (30 minutes)

we use Fiddler to trace the http request and also check IIS logs and found that sometimes the web role didn't get a request,  sometimes the IIS got the request and finished to processe the request but didn't return result to GUI.

it seems the message lost during interaction between UI and web role.

note that this problems comes out just recently.

is there some known issues related with this kind of problems. 

thanks in advance.