SBS 2011 / Exchange 2010 Internal Autodiscover fun...

I recently inherited a poorly designed / managed SBS 2011 environment and I've been having a fabulous time exploring an odd issue related to calendar sharing via MS Outlook 2010 (running via terminal server and Win7 laptops).  A little background on the network setup itself:  we have two public domains; we'll use pubdomain1 and pubdomain2.  Our SSL cert is registered to pubdomain1, so our internal and external urls for mail access (and autoconfig) use pubdomain1.  In a nutshell, the domains in use here are as follows:  pubdomain1.com, pubdomain2.com, pubdomain2.local (internal AD domain).  

Now to the issue at hand...

I am able to share calendars via OWA without issue, but receive an unnamed error when MS Outlook itself is creating the sharing message, although I am able to change permissions manually.  Users are still unable to see any shared calendar information and receive (I've already attempted removing and rebuilding the "audodiscover" virtual directory from EMS per previous posts with no success.  Running "test email autoconfig from the outlook tray returns the following (on both terminal and via laptops):

Attempting URL https://pubdomain1.com/autodiscover/autodiscover.xml found through SCP
Autodiscover to https://pubdomain1.com/autodiscover/autodiscover.xml starting
GetLastError=0; httpStatus=500.
Autodiscover request completed with http status code 500
Autodiscover to https://pubdomain1.com/autodiscover/autodiscover.xml Failed (0x80004005)
Autodiscover to https://pubdomain2.com/autodiscover/autodiscover.xml starting
GetLastError=12029; httpStatus=0.
Autodiscover to https://pubdomain2.com/autodiscover/autodiscover.xml Failed (0x800C8203)
Autodiscover to https://autodiscover.pubdomain2.com/autodiscover/autodiscover.xml starting
GetLastError=12175; httpStatus=0.
GetLastError=0; httpStatus=500.
Autodiscover request completed with http status code 500
Autodiscover to https://autodiscover.pubdomain2.com/autodiscover/autodiscover.xml Failed (0x80004005)
Local autodiscover for pubdomain2.com starting
Local autodiscover for pubdomain2.com Failed (0x8004010F)
Redirect check to http://autodiscover.pubdomain2.com/autodiscover/autodiscover.xml starting
Srv Record lookup for http://autodiscover.ondemandhouston.com/autodiscover/autodiscover.xml Failed (0x80004005)
Srv Record lookup for pubdomain2.com starting
Srv Record lookup for pubdomain2.com Failed (0x8004010F)

I appreciate any thoughts / replies.

Thanks!!