Just started on this forum so please excuse etiquette mistakes, but I think this info might help a lot of people. I have actually solved this problem with the help of another thread (Tor Browser 7 is not starting) but think it needs to be easier to find because it'll help a lot of people (took me forever to solve). I cannot add my comments there since I've just joined.
I could not get Tor to start on Windows 8.1 Pro - saw the 'busy' symbol for a bit, then nothing. No Tor or Firefox processes to be seen under Task Manager.
Turns out that stopping IBM Trusteer Rapport banking security software (program is called Trusteer Endpoint Protection) running did the trick. This software is recommended by my major UK bank (NatWest) so a lot of people will have it. It's easy to disable by going to the search box and searching for trusteer - there are start and stop options.
However this IBM software works, I can imagine other security software might cause similar problems. It would be nice if a way could be found to alert the user to possible blocking software like this. Or at least make it easier to find solutions in places such as this. A lot of people would give up faced with this issue and that's not good for the community. It'd be great if someone with the ability to do so would make this solution easier to find.
Presumably this problem is not specific to a Windows version. Nor, probably, to Tor version (I'm using 7.0.4).
