d3d_texbmaps is indeed not reduced by releasing the old textures when switching the resolution. I have put this on the bug list. But you should still be able to find the problem this way when you don't change the resolution.
I'm getting many reports on Steam from people who have problems when switching between programs and then returning to the game that they get "Error E2005: Can't create DirectX texture unnamed" errors and the game stops. I'm not sure if I understand the discussion here correctly, but is this problem the d3d_texbmaps bug? When will this be fixed? I also don't find this on the bug list? Is there a workaround?
