Before you install, check to make sure all the modules are in the Install\Module folder. It deletes each module zip file as it is installed. The thing to know is that if your DNN installation fails halfway through, it doesn't put the deleted module zips back. If you delete the database to try the install again, you won't have the modules that were successfully installed the first time. What I do is create a copy of the Install folder and name it Install Backup. Then before reinstalling (if it happens to fail for some reason) I copy the backup over the original Install folder.
That's based on my experience, however, search for "missing modules" in these forums and you will find many other helpful resources.
John
My music: http://johnalbertthomas.com/music
My job: http://www.ensafe.com
Environmental, Engineering, Health & Safety,
and Information Technology Consulting