QuickBooks web connector makes an attempt to connect to QuickBooks during update operation. This error code represents the fact that a failure occurred during this connection attempt. Notice that you can get this error if QuickBooks is running on Vista with UAC turned off.
There should be some information in the status window. Take a screenshot (press Alt+PrtSc while the window is selected) of the information and send it along with the QWCLog.txt file (generally in C:\Documents and Settings\All Users\Application Data\Intuit\Quickbooks Web Connector\version directory) to support.