When I click on a part in an assembly, the design tree on the left does not expand.  Only the sub-assembly gets highlighted where the part is located.  To find the needed part, I have to manually expand the tree and search for the part.  A month ago, everything was working fine, and my co-worker's solidworks is working fine too.  The "scroll selected item into view" is checked in Feature Manager.  I have restarted the computer, still no luck.  My last resort would be to reinstall the program, but I'm hoping there is a simple solution.

Any advice would be helpful. Thanks.