Line: 1945
Char: 4
Error: Object expected
Code: 0
URL: http://[servername]/[sitecollection]/_layouts/1033/init.js?rev=%GB3VB3498jfsdfjk
also, it was not possible to modify the Navigation for any SharePoint site.
I tried many options like installation/un-installation of IE9, group policy update, IE settings update etc...but nothing worked & Desktop support team was all set to format my Laptop & install new Windows 7 image.
Then, fortunately I came across an useful article (http://social.technet.microsoft.com/Forums/en-US/sharepointadmin/thread/41e1874f-7825-4bfe-ba4c-37255d198df2) & ran Office Diagnostic Tool accordingly...It fixed the issue !!!!!
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One update...
Today, I installed MS Office Project 2010 & noticed that same above issue is back again. Then, I run Office diagnostic tool & found problem is fixed.