I was importing panos and and I've built the VT many times. Suddenly the message "Current project cannot be built. The project contains at least one spot that is not associated to a spot style" The bug is I never put any hot spot in this project yet, I just import and export panos and cubefaces panos. In fact, it's just after I put geolocalisation on the panos the error occurred. I've changed the Default map hot spot picture and it solved the problem. Honestly I never had this problem before.
I don't want to lead everyone in the wrong direction but I had this exact same bug when I first started using Panotour Standard Edition and it was in version 2.1RC but went away in version 2.1Full (I logged it on the forum at the time)
I was using the 64bit version under Win7 and by a process of trial and error IN MY CASE it was only present on Panoramas that had been Geo-coded (I used Geosetter) and in the Standard edition not Pro. same as Morgan I wasn't even using hotspots I was just using PT to create html and swf files for the web
I realise this may just be a coincidence and nothing to do with this occurrence !