CM 2012 SP1 Reporting services SPN question

Question

Hi
I have a issue where a remote console or web browser cannot see any reports. When logging onto the site locally they can access reports fine with the console. 
Primary site with all roles CM and SQL local. 
SSRS service is running under a domain user account 
In the AdminUI.log there are HTTP 401 unauthorized errors. Will i find this error on the server in any logs?
There is no SPN registered for SSRS service account to the server
My suspicions are that a SPN needs to be registered, but if i register a SPN for (HTTP/server domain user acc) how can i find out if i will have a problem with other web apps (i have MP, DP on box) like suggested below
HTTP is
the service class. The Report Server Web service runs in HTTP.SYS. A by-product of creating an SPN for HTTP is that all Web applications
on the same computer that run in HTTP.SYS (including applications hosted in IIS) will be granted tickets based on the domain user account. If those services run under a different account, the authentication requests will fail. 
http://msdn.microsoft.com/en-us/library/cc281382.aspx

Answer 1

I added the service account to the WAA group and it did not resolve the issue.
I removed the RSWindowsNegotiate setting
and it works fine...  I guess its due to a SPN not being set, I dont want to have any webserver conflictions if I set the SPN for HTTP so i went for removing the above setting.
For information:
After you confirm the problem, you can address it in the following ways:
Register an SPN for the Report Server service under the domain user account. For more information, see How to: Register a Service Principal
Name (SPN) for a Report Server.
Change the service account to run under a built-in account such as Network Service. Built-in accounts map HTTP SPN to the Host SPN, which is defined when you join a computer to your network. For more information, see How
to: Configure a Service Account for Reporting Services.
Use NTLM. NTLM will generally work in cases where Kerberos authentication fails. To use NTLM, remove RSWindowsNegotiate from the RSReportServer.config file and verify that only RSWindowsNTLM is
specified. If you choose this approach, you can continue to use a domain user account for the Report Server service even if you do not define an SPN for it.