If you are having a problem accessing OWA from an sbs 2008 server itself after installing Exchange Server 2007 SP3 then this one is for you. The symptom is that while logged into the server as an administrator and attempting to access owa using the url https://yourservername/owa you get errors or potentially nothing shown. This may also apply to the https://yourservername/remote url too. Other network clients can access it fine as can remote users.
Solution : Open the IIS Service management console and open the yourservernamesites menu. Right Click on the SBS Web Applications link select Edit Bindings. Click on https then edit. For SSL certifcate – click on the drop down show – The choice you should select is SITES and then OK and close out of the IIS management console. Try to open https://yourservername/owa and you should be rewarded with the login screen for OWA.