If you need to unload and/or reload the SSRS 2005 perfmon counters for any reason, here's how:
Use unlodctr against the name of the object as it appears in the list of Perfomance Objects in perfmon. You can also find this name in the .ini files for each object. For SSRS, you have two of these suckers: perf-MSSQLSERVERrsctr.ini (for the web service) and perf-MSSQLSERVERrsSchedulectr.ini (windows service). You can find both of these files in C:\Program Files\Microsoft SQL Server\MSSQL.?\Reporting Services\ReportServer\Bin\
So, to unload the SSRS web service counters, I'm going to crack open perf-MSSQLSERVERrsctr.ini and see that the name of this object is "MSRS 2005 Web Service"
I'll therefore run this to unload it:
C:\>unlodctr "MSRS 2005 Web Service"
Next, I want to reload it. I do so by pointing lodctr.exe at the ini file:
C:\>lodctr.exe "C:\Program Files\Microsoft SQL Server\MSSQL.3\Reporting Services\ReportServer\Bin\perf-MSSQLSERVERrsctr.ini"