a bug in WORD 2007, 2010

I like the equations in Word 2007/2010. and i like the Track changes because it is very useful in reviewing /revising papers.

But it is Very annoying that an error occurs when you use Track changes and new equations.
It wasted me several hours doing this meaningless work.

Don't know why MS would not attempt to fix this bug.


Be careful from now on till MS fix it:
1. Save frequently
2. do not use track changes for equations