I installed Sitecore 8.0, rev. 150427 and tried to install a package I created in another Sitecore instance. The package Installation Wizard got to the “Installing…” screen and never completed. I let it run for several minutes and it never completed. I reviewed the Sitecore log files and found no errors regarding the package installation itself, however, my log files were flooded with MongoDB connectivity errors.
Turns out, I needed to install MongoDB on my local. Installing MongoDB not only fixed my issue with the Sitecore Package Installation Wizard, but it also significantly reduced the amount of log entries in my log files.
When installing MongoDB for your Sitecore instance, double-check which version of MongoDB you should be running as Sitecore specifies version compatibility between Sitecore and MongoDB – https://kb.sitecore.net/articles/087164. Also, consider installing MongoDB as a Windows Service and set it to run on startup by default as this will ensure you don’t run into this issue again in the future – https://docs.mongodb.org/v3.0/tutorial/install-mongodb-on-windows/#configure-a-windows-service-for-mongodb.