1. Verify that the values under HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders use valid drive letters.
2. If there are invalid drive letters, change them to point to valid drives
3. Try to install the software and check if that helps.

Basics:

Licensechecks are done each time the application is accessed by a user. Having an invalid license stops the whole product from working. And invalid license will never have any impact on the CRM, it only limits the addon itself.

Reasons for an invalid license :

• Wrong license OrganizationUnit
• Usercount has execeeded the granted licenses (Stops whole product, not only for the excessive users on all license models)
• Upgrading the product after having the support contract expired
• In Case of a time limited license (and a trial) : Reached the end of the license lifetime.

Licensetype normal license (aka perSite license)

Requires a license for each active CRM user, no matter if he uses the product or not. If new CRM users are added, the license needs to be extended with more users as well.

Disabled, ReadOnly users and Administrative users do not require a license.

Licensetype perUser license

Requires only as many licenses as you actually want to have, but starts at a minimum of 10 licenses and is double the price of a site license.

The license is a named user license and the license is activated via a checkbox on the Systemuser entity for a specific user. You may activate as many users for the access as you have licenses.

Exceeding the granted license count stops the product for all users.

The problem due to the fact, that MS CRM is using an HttpModule for multitenancy scenarios. This http module will be called with an anonymous user account and therefore fail when trying to request e.g the metadata webservice.

Solution: To make it work, a new entry (remove CrmAuthentication) has to be specified within the web.config file of the specific Add-On.

<system.web>
 ...
 <httpmodules> 
 <remove name="CrmAuthentication" />
 </httpmodules> 
 ...
</system.web>