What causes "The INF file you selected does not support this method of installation." error?

In order for the "Right Click/Install" method to work, there must be a [DefaultInstall] section in the INF file and, potentially some other "Default" sections:

[DefaultInstall.Service] 
[DefaultUninstall]
[DefaultUninstall.Service] 

http://msdn.microsoft.com/en-us/library/windows/hardware/ff547465(v=vs.85).aspx

If there is no [DefaultInstall] section, you get the message “The INF file you selected does not support this method of installation.”

You might try to select the inf file from Device Manager:

Right-click the device, select Update Driver Software, then Let me pick, click Have disk, Browse to the inf file and install.

If this doesn't work, I don't believe you can fix the inf file. The product you have probably doesn't match your operating system (it might be 32-bit when your Windows 7 is 64-bit).

You can also give more information, such as posting the inf file (actually the entire product, if possible).

INF files format reference: http://msdn.microsoft.com/en-us/library/ms764958(v=VS.85).aspx

It would help to read the Creating Setup Applications (http://msdn.microsoft.com/en-us/library/aa376920(v=VS.85).aspx) page to learn the sequence followed, so you can step through the INF manually. I suppose a programmer could attach a debugger to setup and figure out what its failing on.