Hi,
If other site project files (something.wpp) are opening fine but you have an issue with one other file, this maybe down to some kind of corruption within that file, did you make numerous incremental updates of this site? and if so, does an earlier backup version open correctly?
I would imagine you have already installed the included fonts for the Hike template to your system otherwise, you may not have been able to open/edit the template from the off.
Also, have you added anything to the site's pages that may use the SWR function of Serif (I haven't time to check the whole site) or an incorrectly configured Google map reference, any of these "could" cause a bug issue.
You could also try and disable the automatic update checking of the software (Tools > Options > General) then reboot the PC and see if that helps.
Apart from that, there is not a lot we can do from this end but hope it helps a little.