APPCRASH (supposedly Qt5Gui.dll)

[MAGNAT2645]

When opening any material, VMT Editor throws fatal unknown error (doesn't show it) and then crashes.

Windows states that this is APPCRASH and the error happens in the Qt5Gui.dll module.
I think the crash occurs right before rendering a texture.
It works fine if you don't open any material with texture.

If you open a material without $basetexture and then use Diffuse field to choose the texture, VMT Editor throw these errors:

and closes when i click OK.

Is this something wrong with drivers? They're pretty old but there's no updates so I use what I have.

OS: Windows 7 x64