It's not just 2010. Inventor has ALWAYS done that on certain parts. Typically it happens with parts copied from the content center. It really is a shame that they STILL haven't fixed that issue.

I found a way around that, making it not less irratable, but at least enabling me to make progress. If you are working in your new assembly, you go into editing the individual parts. You can either edit from within the assembly, or you can open the part on its own. You then slowly click on the (unchanged) name of the part in the browser as if you are in Windows Explorer, allowing you to edit in, a name change. Delete the old name and type in your new name. It then keeps the new name of the part. (Now how difficult could that be, to program that little action into your source code, Autodesk????)

This is the response I got from Autodesk 1 month ago about this issue. Supposedly SP1 for 2010 fixed the issue with standard parts. Now its just Content center parts that have this bug.

"The renaming has been addressed for standard Inventor files. The renaming of Content Center components is presently being review by development for a Hotfix. If approved look for it in a two to three month time frame. That is the best time frame I can give considering it can be stopped at any time or not published at all. Thank you for bring this to our attention."