CAUSE:
ColdFusion installs a global wildcard handler mapping which apparently overrides many of the standard .NET handlers

To solve this problem you must remove the cold fusion inherited handler mappings from the Web Tracks site. The steps described below will only remove the mappings from the Web Tracks site so it will not break cold fusion sites.

1. Open IIS Manager (inetmgr.exe)

2. Double-Click on the Web Tracks Site (by default it is under the 'Default Web Site')

3. Double-Click the 'Handler Mappings' Section

4. Delete all entries that are like "AboMapperCustom-XXXXXX" with "*" for the Path

Source Article…
http://stackoverflow.com/questions/2654514/getting-the-webresource-axd-handler-must-be-registered-in-the-configuration-to