I'm having the same problem. I've wiped arma2 off my drive and started fresh, but still every save (manual or auto) says I'm missing CAweapons3. This didn't start until after I patched to 1.5, but it didn't start happening immediately after patching either...
Is CAweapons3 an actual component floating around out there in the addon community, or is it simply the name of one component with the wrong number on the end?