Exchange 2010 OWA CAS Proxy

Hi all and thanks for any assistance you might be able to give me.

I have exchange 2010 - 2 CAS mailbox servers in 2 locations - same domain - DC's in both locations.  We had an outage and my webmail seems to be hosed.  Site A is internet facing Site B is not.  All webmail access goes through site A - my setup before would proxy back to the first server and load the mailbox.  It now appears to have lost permissions.  here is the error I get when i try to login externally... im sure youll need more info just ask away :) and thanks again

Request
Url: https://xxxx.xxxx.com:443/owa/ev.owa?oeh=1&ns=HttpProxy&ev=ProxyRequest
User host address: x.x.x.x
User: xxxx,xxxx
EX Address: /o=xxxxxxxx/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=xx, xx
SMTP Address: xxx@xxx.com
OWA version: 14.0.702.0
Second CAS for proxy: https://internaladdress

Exception
Exception type: Microsoft.Exchange.Clients.Owa.Core.OwaProxyException
Exception message: The proxy CAS failed to authenticate to the second CAS (it returned a 401)

Call stack

No callstack available

Inner Exception
Exception type: Microsoft.Exchange.Clients.Owa.Core.OwaAsyncOperationException
Exception message: ProxyPingRequest async operation failed

Call stack

Microsoft.Exchange.Clients.Owa.Core.ProxyPingRequest.EndSend(IAsyncResult asyncResult)
Microsoft.Exchange.Clients.Owa.Core.ProxyEventHandler.SendProxyPingRequestCallback(IAsyncResult asyncResult)

Inner Exception
Exception type: System.Net.WebException
Exception message: The remote server returned an error: (401) Unauthorized.

Call stack

System.Net.HttpWebRequest.EndGetResponse(IAsyncResult asyncResult)
Microsoft.Exchange.Clients.Owa.Core.ProxyUtilities.EndGetResponse(HttpWebRequest request, IAsyncResult asyncResult, Stopwatch requestClock)
Microsoft.Exchange.Clients.Owa.Core.ProxyPingRequest.GetResponseCallback(IAsyncResult asyncResult)