there are a number of them available free.. sometimes called htc wifi router,..
there are many times when something hicups and throws the whole network services into a mess. other than hardreset, you just have to play around with uninstalling/reboot/ect.. and try connecting your phone to a real router then back... bla bla... if I actually knew what i've done to fix it there'd be a thread, but evertime i've 'fixed' it, it seemed like magic.
oh, but I bet the 'hotspot' app does succed in making a hot spot around the tp1
keep a fire extiguisher handy