All of this triggered a ten year old memory of a similar experience on Win 7.
Try this -- remove all the copies of EuCon dlls(you really shouldn't need this at all anyway), CSI dlls', make sure to leave the CSI folders alone.
Start Reaper -- what happens ?
Does it load, if so, this is the thing we ran into == there were some "ghosts" of the roaming dirs for some reason -- tres bizarre indeed.
We never did find a fix, it just resynched at some point and was never a problem again.
On the other outcome -- if it doesn't work anyomore, go ahead and install the latest, maybe removing everything will change the equation somehow.
I know this sounds a bit crazy, but hey, its Windows right ?