Failed to map the path '/ReportServer/App_GlobalResources/' while Trrying to browse the Reporserver and reports.

problem lies in the permissions of the ASP.NET user account.

First step was to delete the ASPNET user account and then run the aspnet_regiis utility in the framework folder:

c:\WINNT\Microsoft.NET\framework\v2.0.50727\aspnet_regiis -i

This will re-register ASP.NET with IIS and re-create the ASPNET account.

Next you need to give permissions to the (nicely refreshed) ASPNET user account to access this folder with Modify permissions:

C:\Documents and Settings\All Users.WINNT\Application Data\Microsoft\Crypto\RSA\MachineKeys

A quick restart of IIS (quick-tip: simply type iisreset in a run dialog to restart your IIS)

OR

giving the ASP.NET user account permissions over the 'C:\Documents and Settings\All Users.WINNT\Application Data\Microsoft\Crypto\RSA\MachineKeys'

OR

click the Security Tab under the Properties of the C:\Documents and Settings\All Users\Application Data\Microsoft\Crypto\RSA and add the ASP.NET account with full control.

OR

In the folder --> C:\Documents and Settings\All Users\Application Data\Microsoft\Crypto\RSA\MachineKeys
... I found a key that was 0 KBytes,
simply deleted it (which is then recreated when accessing the website)