Also check in the SSRs config file.
Probably the localhost name is used there in stead of teh hostname.
Normally you can alter this config file with the GUI from configuration manager, but i also have found that the modifications in this are not always saved.
So these steps should be performed then:
Stop SSRs services
find the config file in the SSRs installed directorie , normally C:\program files\ms sqlserver\sqlversion\..
Don't have the exact path @ hand but i remember the directoryname was so obvious like SSRs you dont really need it.
take a copy of the config file just in case..
Open the config file in wordpas or so and search for the 'hostname' value.
Change to the computername
Save the file
Start SSRs services