On site recently I had a problem that I could not access the site settings in reporting services if I used Internet Explorer from an client PC. IE worked fine on the server and other browsers were OK on the client, just not IE. Initially I though it was just rights, but that was not the case
Turns out this is down to Kerberos negotiation as discussed in the MSDN article. To fix the issue, on this site where we did not need Kerberos, we just disabled Kerberos negotiation in the [Program files]\Microsoft SQL Server\MSRS10.MSSQLSERVER\Reporting Services\ReportServer\RSreportServer.config file, e.g.
<RSWindowsKerberos /> <RSWindowsNTLM />
If you need Kerberos you need to sort out the SPNs as detail in the MSDN post