It's rare for that to happen, but if it does I'd first just reload the page and fill in the DB info again, and let it do its install over. Or go back one page and go from there.

If it's halting due to some sort of error, it's most likely logged in the /logs/ folder in zcInstall-DEBUG-xxxxxx.log files.

It might be a result of incomplete files from a bad FTP upload, too.