Before attending Sitecore .NET Developer training, developers install the training sample site. The sample site is a prepopulated Sitecore instance that helps students learn Sitecore concepts and complete the training labs.
The installer works well for the large majority of students; however, for certain system configurations the installation may not complete successfully.
The absolute best source for troubleshooting Sitecore installations is the Installation Troubleshooting Guide that developers can find on Sitecore's SDN site. The troubleshooting guide lists all common error messages and troubleshooting steps.
If you can not access the troubleshooting guide, request a login and password for the Sitecore Developer Network from your training adminsitrator.