Send Error - connection interrupted by server (or server has timed out)

Evere since Verizon changed their SMPT and POP ports I have had this problem. Using Outlook 2010, I have one sub-account that can receive, but not send. Yes, I have been through every configuration scenario you can imagine (I am an IT professional so please don't respond with "Have you checked this box..." type answers.) From nowhere, Outlook will display a send/receive error followed by a prompt to re-enter the password for the account. It will do this at least twice and sometimes three or four times. I've have received errors such as listed in the title above as well as "an encrypted connection with this server is unavailable".  This happens only on one sub-account, which has the same settings as the master as well as the other sub-accounts. Emails languish in the outbox until some random amount of time passes and Outlook does its scheduled send/receive and then magic happens and the emails go out. I'll get a day or two of it working without said delays, then only to discover I have to reset my password to perform a send (not a receive. Receive always works.) Now, before you say I've been hacked, I thought of that and ran a test. Logging into via the web, I noted the last access time and date. I waited until the password failed, then re-accessed the account using the master to find that the time/date of last access was my access. Then sending from the master to the sub-account, sure enough, I was able to receive the email, but sending was a non-starter. There was nothing intervening. And let me reiterate, this happens with only one sub-account and I have several. Not to mention my computer has been scrubbed by various software packages (Wise, Spybot, Norton) only to find...nothing. No root kits, no bots, no registry changes, no malware. I've even used software (smartmon) to monitor in/out internet traffic at the packet level PLUS my machine sits behind TWO firewalls and a second router. If I've been hacked, these people are really, really well trained. I don't think the account being hacked is the issue. Anybody have ANY clue why an account can receive with a password, but to send, requires changing the password first? This has me beyond stumped.