As any user of Orion 8.x can attest the problem with the error "Cannot load network map..." can be exasperating. I saw somewhere in Thwack that this was associated with a memory leak in the 'dllhost.exe' process. If you kill the process then refresh all is well.
I also saw a supposed work around to modify the COM+ pool - which did not work at my site. It only made things worse.
In any case we started to use the following command from a priveledged command prompt to kill the process which then will start a new one.
That is a very clever work around.
I have this same issue, however
go to Administrative tools -> Component Services -> Com+ applicaiton -> right click on Solarwinds Orion NPM -> Properties.
under pooling and recycling tab -> LifeTime Limit(minutes) ->
set the current value to 1440.
worked magic for me. I have to go back and redo this after each service pack or config wizard run...I might adopt your method instead.