We came across this problem way back in 2008 with Vista where fax pages are forced into landscape orientation. On Vista, the answer was to install Microsoft Office Document Imaging (MODI) and use that viewer instead of the Windows Fax and Scan applet.
In a Windows Server 2008 terminal server environment, MODI doesn’t work reliably. We’ve heard that installing Windows Server 2008 Service Pack 2 resolves the problem, but that’s a much greater undertaking.
We’ve started installing Brava Reader to view the TIFF files produced by SBS fax. This quickly resolves the issue.