I've written to Dazz, hopefully he can figure out what is happening. It could be the buffer they use to retrieve the system video modes is not big enough, just to think of a possible reason...
The file I'm patching is ati2mtag.sys. Basically what I do is to increase the number of modes the driver polls from the registry, like this:
'.text:0000000000052EE7 lea r8d, [rsi+3Ch]
'.text:0000000000052EEB lea rdx, aDalnonstandard ; "DALNonStandardModes"
PatchFileByte ( TargetFile, &h000424EA, 127 )
So that replaces 3Ch (60) by 127. I can't use a bigger number there cause it's a signed char so 128 is already negative.
Then I patch the instances where 140h and 190h are checked (320 and 400) to disable doublescan for those modes. There many of them, look like this:
'.text:00000000000D1369 cmp r8d, 140h
'.text:00000000000D1379 cmp r8d, 190h
DATA 000C096C, 40, 00, 000C096D, 01, 00
DATA 000C097C, 90, 00, 000C097D, 01, 00
I wouldn't mind uploading the full patch code at some point so someone else can help with this.