One scenario that will often fail is the deployment of Dynamics AX 2009 SSRS reports to your Microsoft SQL Server Reporting Services. For that purpose the AxReports deployment application is launched.
During the deployment process the CLRBridge DLL is loaded and unfortunately it is the CLRBride from the Dynamics AX 4.0 Client. The reason why the CLRBride from Dynamcis AX 4.0 is taken is because the BIN folder of the Dynamics AX 4.0 Client is listed in the PATH environment variable before the BIN folder of the Dynamics AX 2009 Client.
In order to fix this it is enough to simply change the order of the Dynamics AX Clients in the PATH environment variable, so the BIN folder of the Dynamics AX 2009 Client is listed before the Dynamics AX 4.0 Client.
The inability to deploy SSRS reports is however not the only scenario you can run into issues when the wrong CLRBride is loaded. I have also seen issues were the Dynamics AX 2009 Visual Studio Extensions (that are accessing the AOT) were having trouble, up to ending in a crash of the Visual Studio IDE.
A common error message showing up in the Visual Stuido IDE is:
At the same time the following messages are logged in the Application event log: