SQL Reporting services is great, but it is actually quite common to mess up the installation due to the steps taken in installation. Always make sure you do not install either sharepoint or CRM on the same website as CRM. (It is possible to get it to work but not recommended).
What can happen is the following:
1. Installing SQL 2005, in the process installing SQL RS on port 80 = http://localhost/reports and http://localhost/reportmanager.
2. Installing either CRM or a SharePoint site on port 80 of the same computer.
= SQL Reporting Services doesn't work anymore...
So, what to do.
First, if you want your CRM or SharePoint site to be located on port 80, don't install SQL RS on port 80. Create some other webapplication using host headers or TCP-ports and install SQL RS to that website instead. Then install CRM or SharePoint to port 80. No conflict = no problems.
If you happen to mess it up anyway, or is asked to fix a messed up installation, you can do magic with the tool RSConfigTool which resides in the SQL Binn-directory (usually: C:\Program Files\Microsoft SQL Server\90\Tools\Binn). Start it, and reconfigure it properly.
Have fun reporting!
CRM and SharePoint Consultant