Can try this
1. run regedit from the command prompt in windows. (Start>Run>type in Regedit)
2. navigate to HKEY_CURRENT_USER>Software>Microsoft>Windows>CurrentVersion>Internet Settings.
3. Have a look in the right-hand window and see if there are two strings named MaxConnectionsPerServer and MaxConnectionsPer1_0Server. Double click on the strings to change the value. If they are not there go to step 5.