Workflow Soluiton

I have a Web form that will throw errors with the message "Error,Tuesday, September 17, 2013 8:31:52 AM,Exception at Run method with message :The underlying connection was closed: An unexpected error occurred on a send.".  The errors are thrown thousands of times in the space of a few minutes.  The only way I've found to stop them is to reset IIS.

Can anyone explain the root cause of this error?  The web form still works, but I want to resolve these error messages. 

Do you have access to a full stack trace? Also, can you specify what version of WF this is occurring in?

I am working in Workflow 7.1.1500.2071.

As far as trace information goes, the only data I am getting is :

Log Name:      Application
Source:        SOD_ConsumerFeeder
Date:          9/18/2013 8:34:32 AM
Event ID:      0
Task Category: None
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      COLWKF301.jcp.com
Description:
Error,Wednesday, September 18, 2013 8:34:32 AM,Exception at Run method with message :The underlying connection was closed: An unexpected error occurred on a send.
 

Sometimes there will also be a second error being thrown at the same time:

Log Name:      Application
Source:        SOD_ConsumerFeeder
Date:          9/18/2013 8:34:32 AM
Event ID:      0
Task Category: None
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      COLWKF301.jcp.com
Description:
Error,Wednesday, September 18, 2013 8:34:32 AM,Exception at Run method with message :Collection was modified; enumeration operation may not execute.