Inventor Error. Cannot modify

[crazyStone]

One of your settings/ file paths is messed up. I would check all of your settings under the inventor symbol and then "options" as well as check your project, I know you already did, but that sounds like a an problem that comes from an unchecked "Project file" option. Also how far apart are your "andy mark" parts from your assemblies? depending on the path its taking/ where its saving etc weird things can happen especially since andy mark parts are downloaded as .step, and not in a native format.