I also got this error several times while debugging. (Administrator permissions required...)
I thought it had something to do with the permissions and just ignored it.
It has surely something to do with what Carlos stated
It happened again, but now I think I know what's going on..
At start It works fine, but after some time the user's session timeouts and I get this error message from Service Studio.
If I login again in the espace and try debugging it works again.
I'm using ServiceStudio 126.96.36.199