Hmm - Your words should have gotten this article https://accountants-community.intuit.com/articles/1785173-please-wait-while-we-launch-lacerte 

If that doesn't work, I would try a force install https://accountants-community.intuit.com/articles/1607261-how-to-perform-a-force-install-of-lacerte That process may clean up your install and give better results. 

There MIGHT be a problem with your Anti Virus software. If it persists, turn off the AV software while you install.