I think it may be dirty on the lens, or some misalignment on the cannon, that is making difficult for the system to read the security ring.

Oh yeah, i meant that my system doesnīt boot cd-rīs. But yeah, it sure reads them. (althrough i never did the swapping trick with this system).
But i think a working laser is important indeed.

I was thinking about cleaning the lenses with a dry q-tip, maybe i am wrong ?

Time to google it.