Another 10061Connection refused error

We have just setup a new SBS 2011 running Exchange 2010.  We have set up all the users, mailboxes etc etc.  We are at the stage of bringing in emails.  We are using Smart Pop2Exchange 7.21.  Went we restart the server everything works fine for about 20 mintues then we get "SmartPOP2Exchange Enterprise Edition (7.2.1.477) 3/3/2011 3:12:07 PM   Error while opening SMTP connection to 'Server': Socket Error # 10061  Connection refused.  --> No connection could be made because the target machine actively refused it.  You tried to connect to the wrong server or the SMTP service isn't available on that server.Please check for a correct the SMTP host name and port (usually 25 or 587?) and make sure the SMTP service is available."  and it stays that way until we reboot.  We have started the Microsoft Information Store, restarted the SmartPop2Exchange.  Most messages appear to be firewall related, we have turned off the firewall(s) no change.  We have disabled the Microsoft Spam Filtering using "Set-ContentFilterConfig -Enabled $false" and "Set-ContentFilterConfig -InternalMailEnabled $false" and "Set-ContentFilterConfig -ExternalMailEnabled $false".  We have downloaded an applied all the Windows Updates .. any ideas what to try next?