If it's first loaded as detecting for seconds, but finally returned a blank page. Please try to remove the cache files using command below.

1. For all users in a server:
rm -rf /home/*/.rvsitebuilder/cache
rm -rf /home/*/.rvsitebuilder/tmp

2. For the individual user:
rm -rf /home/{user}/.rvsitebuilder/cache
rm -rf /home/{user}/.rvsitebuilder/tmp

And access to the RVsitebuilder again.