There is an option to enable more logging... I don't remember exactly where (I don't have access to Orbiter right now), but it should be something similar to "Extra >> Debugging options >> Verbose log".
Also, there is a D3D9 log, which has several debug levels, controlled by an option in... (again, from memory) "Visual Settings >> Advanced (this is a button which opens a new window) >> Log level". Set it to the full output, try a scenario and post both logs please (the D3D9 log is a .html file, located in /Modules/D3D9).
(0: 0.0s 00.00ms)(0x21FC) [Not Compiled With nVidia API]
(1: 0.0s 07.73ms)(0x21FC) ================ clbkInitialise ===============
(2: 0.0s 00.03ms)(0x21FC) Orbiter Version = 160828
(3: 0.1s 42.67ms)(0x21FC) Index:0 640 x 480 60Hz (22)
(4: 0.1s 01.79ms)(0x21FC) Index:1 640 x 480 72Hz (22)
(5: 0.1s 03.93ms)(0x21FC) Index:2 640 x 480 75Hz (22)
(6: 0.1s 16.26ms)(0x21FC) Index:3 720 x 480 56Hz (22)
(7: 0.1s 20.60ms)(0x21FC) Index:4 720 x 480 60Hz (22)
(8: 0.1s 20.83ms)(0x21FC) Index:5 720 x 480 72Hz (22)
(9: 0.1s 23.00ms)(0x21FC) Index:6 720 x 480 75Hz (22)
(10: 0.2s 22.54ms)(0x21FC) Index:7 720 x 576 56Hz (22)
(11: 0.2s 11.97ms)(0x21FC) Index:8 720 x 576 60Hz (22)
(12: 0.2s 21.55ms)(0x21FC) Index:9 720 x 576 72Hz (22)
(13: 0.2s 20.44ms)(0x21FC) Index:10 720 x 576 75Hz (22)
(14: 0.2s 20.11ms)(0x21FC) Index:11 800 x 600 56Hz (22)
(15: 0.3s 19.44ms)(0x21FC) Index:12 800 x 600 60Hz (22)
(16: 0.3s 07.11ms)(0x21FC) Index:13 800 x 600 72Hz (22)
(17: 0.3s 01.77ms)(0x21FC) Index:14 800 x 600 75Hz (22)
(18: 0.3s 02.63ms)(0x21FC) Index:15 1024 x 768 60Hz (22)
(19: 0.3s 01.86ms)(0x21FC) Index:16 1024 x 768 70Hz (22)
(20: 0.3s 01.75ms)(0x21FC) Index:17 1024 x 768 75Hz (22)
(21: 0.3s 01.66ms)(0x21FC) Index:18 1152 x 864 75Hz (22)
(22: 0.3s 01.66ms)(0x21FC) Index:19 1176 x 664 60Hz (22)
(23: 0.3s 01.60ms)(0x21FC) Index:20 1280 x 720 60Hz (22)
(24: 0.3s 01.54ms)(0x21FC) Index:21 1280 x 768 60Hz (22)
(25: 0.3s 01.64ms)(0x21FC) Index:22 1280 x 800 60Hz (22)
(26: 0.3s 01.57ms)(0x21FC) Index:23 1280 x 960 60Hz (22)
(27: 0.3s 02.05ms)(0x21FC) Index:24 1280 x 960 75Hz (22)
(28: 0.3s 01.98ms)(0x21FC) Index:25 1280 x 1024 60Hz (22)
(29: 0.3s 01.74ms)(0x21FC) Index:26 1280 x 1024 75Hz (22)
(30: 0.3s 01.55ms)(0x21FC) Index:27 1360 x 768 60Hz (22)
(31: 0.3s 01.59ms)(0x21FC) Index:28 1366 x 768 60Hz (22)
(32: 0.3s 01.62ms)(0x21FC) Index:29 1600 x 900 60Hz (22)
(33: 0.3s 01.86ms)(0x21FC) Index:30 1600 x 1024 59Hz (22)
(34: 0.3s 00.96ms)(0x21FC) Index:31 1600 x 1024 60Hz (22)
(35: 0.3s 00.54ms)(0x21FC) Index:32 1600 x 1200 59Hz (22)
(36: 0.3s 00.55ms)(0x21FC) Index:33 1600 x 1200 60Hz (22)
(37: 0.3s 00.29ms)(0x21FC) Index:34 1680 x 1050 59Hz (22)
(38: 0.3s 00.63ms)(0x21FC) Index:35 1680 x 1050 60Hz (22)
(39: 0.3s 00.45ms)(0x21FC) Index:36 1920 x 1080 60Hz (22)
(40: 0.3s 00.29ms)(0x21FC) Index:37 1920 x 1080 59Hz (22)
(41: 0.3s 00.53ms)(0x21FC) Index:38 1920 x 1200 59Hz (22)
(42: 0.3s 00.42ms)(0x21FC) Index:39 1920 x 1200 60Hz (22)
(43: 0.3s 00.30ms)(0x21FC) Index:40 1920 x 1440 59Hz (22)
(44: 0.3s 00.53ms)(0x21FC) Index:41 1920 x 1440 60Hz (22)
(45: 0.3s 00.58ms)(0x21FC) Index:42 2048 x 1536 60Hz (22)
(46: 0.3s 00.31ms)(0x21FC) Index:43 2048 x 1536 30Hz (22)
(47: 0.3s 00.54ms)(0x21FC) Index:44 2048 x 1536 29Hz (22)
(48: 0.3s 00.43ms)(0x21FC) Index:45 2560 x 1440 59Hz (22)
(49: 0.3s 00.31ms)(0x21FC) Index:46 2560 x 1440 60Hz (22)
(50: 0.3s 00.52ms)(0x21FC) Index:47 2560 x 1600 60Hz (22)
(51: 0.3s 00.31ms)(0x21FC) Index:48 2560 x 1600 30Hz (22)
(52: 0.3s 00.25ms)(0x21FC) Index:49 2560 x 1600 29Hz (22)
(53: 0.3s 00.27ms)(0x21FC) Index:50 3840 x 2160 60Hz (22)
(54: 0.3s 00.31ms)(0x21FC) Index:51 3840 x 2160 30Hz (22)
(55: 0.3s 00.31ms)(0x21FC) Index:52 3840 x 2160 29Hz (22)
(56: 0.3s 00.35ms)(0x21FC) Index:53 1440 x 900 60Hz (22)
(57: 4.5s 4236.83ms)(0x21FC) Scenario = .\Scenarios\(Current state).scn
(58: 4.6s 28.83ms)(0x21FC) D3D9Client destructor called
(59: 4.6s 00.05ms)(0x21FC) --------------ExitModule------------
(60: 4.6s 00.48ms)(0x21FC) Log Closed