Hi there, which build of RF2 are you using?
I´ve heard of some problems like yours but never had them myself.
Plz take a look in your RF2 root folder wether there is a launch rfactor.exe. In some older builds this file was there , i newer builds in the root there is an etxra Launcher folder, in which the file is packed.
Then try to point the updater to this launcher folder or simple copy the launch rfactor.exe to the root. Then everything should work fine.