Content Manager can be installed anywhere on your PC !
Never encountered such a problem and in fact, I never heared someone experiencing the same problem as yours.
Could you try installing it somewhere else than in AC folder itself ? ....
As long as you mention in CM the place where your Assetto Corsa folder is placed on your PC, no problem at all.
Mine is for a long time in its own folder on D: drive .... and never had any problem at all.