I believe you're going to need to provide some more info. It's been awhile for me with the Teamcenter side and different divisions of GM allow/deny suppliers different options, not to mention things may not be the same as when I was using GM's version of Teamcenter.
Are you workin in Teamcenter or in Native NX???? Seems to me like you're getting a read/write permission message while trying to change a part in Teamcenter. Did you go through a Teamcenter to Native NX export process or just find the file in Teamcenter and open in NX? If you just opened it, then you're probably using the file from GM's database and don't have permissions to change it. Never did run into any downloading with GM either - the export process was the downloading essentially - and THEN I opened the file in Native NX.
See if you can export the original part (not cloned part) out of Teamcenter into Native NX. (Never have cloned nor heard of people cloning anything within Teamcenter, but not saying it isn't done). Exporting out should get rid of GM's read/write access restrictions and allow you to change the part as you wish - I'd never work in Teamcenter, always Native NX. Can you not add this "file" as a component to a new NX file and THEN create your dwg if the above isn't an option? Again, this error is something I've never seen before, but like I said, I never work in Teamcenter - always export the parts out to Native and then start doing as I wish.
I highly doubt that this is the Toolkit - that's just a set of tools to help you prepare and/or check drawings and models for import into Teamcenter.
Tim Flater
NX Designer
NX 8.0.3.4
Win7 Pro x64 SP1
Intel Xeon 2.53 GHz 6GB RAM
NVIDIA Quadro 4000 2GB