This is ridiculously obscure, but I remember once-upon-a-time DEP used to mess with Ultima Online (I'm pretty sure CTD was the result) until I made it an exception. It appears on my existing OS installation I don't have any exceptions listed, so maybe a Windows Update made it a bit smarter at some point preventing the need to list regular Games/Applications.
Windows 7 Instruction : My Computer -> System Properties -> Advanced System Settings -> Performance Settings -> Data Execution Prevention : Where you can manually add UO as an exception subject to Data Examination.
Strange that no longer gets in the way though, in the end I had about 6 Applications listed as exceptions because it prevented them from operating properly; DEP thinking they were doing something harmful. Although my last OS HDD did suffer a mechanical failure ages ago (R.I.P. 2nd Minecraft Map), so maybe since then a Windows Patch fixed the whole DEP interference issue...