Please right-click on the System Tray Icon for WTFast and select exit. (The WTFast System Tray Icon should disappear).
Next hit Windows Key + R and type in the following: “C:\Program Files (x86)\WTFast\wtfast.exe log-verbose” (if you installed WTFast in a different directory you will need to type in that instead).
Hit enter and that will launch WTFast in logging mode.
Try and use WTFast the same way you normally would and when it crashes make sure that it is completely closed on your system. This will then generate a file on your desktop, called 'wtfast_debug_log.wtflog'.
Please send that file at email@example.com with an explanation of the issue you are seeing.