I've had this problem for a very long time when my previous driver started acting flaky and I was forced to load the latest one directly from Synaptics. The replacement didn't allow any way to disable tap-to-click. There used to be a "tray-tool" overlay
where I could simply right+click and disable that option.
I was getting so frustrated, I started searching for a way to toggle it off in the registry, but we know how dangerous that can be. I started looking at all of the files that came with the latest driver and I ended up at \Program Files\Synaptics\SynTP. I
noticed there were several executable files there, so I started testing them.
I've discovered that SynTPEnh (06-18-2009) is the overlay tool. If you launch it, it'll give you the option of having it load once, or each time on start-up into the system tray. Also, it may trigger another executable, SynTPHelper (02-25-2013) as they appear
to be companion files.
Long story short; it loaded into the system tray, then I was able to right+click and uncheck tap-to-click. I realize that not all of you may have access to this file, but it's got to be there for SOME of you.
FYI - my driver version is 16.3.15.1, so you could actually download the entire suite from Synaptics, unzip it and get those two files. Good luck!
P.S. I'm on Windows 7, but this is also the Windows 8 software suite.