PC running Win7, Outlook 2010, NIS... mail with attachments not sent

Good Day… firstly apologies for perhaps posting the same type of question, but I could only find solution in old threads.

I am running a pc with Win7, Outlook 2010 and the latest NIS. I am not sure but it seems after the recent patch update I cannot send mails with any type of attachment. Test mails works fine, but mails with attachments goes to the Send folder, then Norton pops up with a message stating that transmission to the mail server has been interrupted.

So far I have disabled the scanning of outgoing mail, but no luck. Please advise what I could try next?