Is the drawing from assembly with subassemblies in it? Solidworks opens the actual parts and assemblies when you open the drawing into memory as far as I know.
And if you have some part used in main assembly, and you have also used that same part in subassembly and have that subassembly placed in main assembly it gives that error. Atleast I had that error message then.
Littlebit tricky to explain
You should get that error when opening the actual assembly. Can you provide screenshot from design tree?
I do have the same parts both in the main assembly and the sub assembly, but I have been working with this assembly/drawing for a couple of months now, and have just started seeing this warning.
I only get the error when opening the drawing. Last night I opened the assembly first then opened the drawing and had no issues. This morning I did the same thing, and got the warning so I am not sure what is going wrong.
It wouldn't be that bad if the warning box only popped up a couple of times, but when it is used for a part that is used over 100 times, then it is a bit of a pain!
This has happened to me in the past. What I do is close down SolidWorks and all of its processes in the task manager and then re-opened SolidWorks and it went away.
I did this as well. Killed all processes related to solidworks, and then restarted my computer and I still had the same issue