I am having the same issue as MadKiwi, and like him, no one seems to be able to solve the problem. (it's been, what, almost 6 years since his post?)
When I open an existing mail merge Word 2007 document from its folder, the mail merge task pane is not open. If I open the same document after first opening Word, the task pane appears.
In the first scenario, after I click on Finish & Merge, and then Edit Individual Documents, if I need to go back to the original mail merge document, the task pane has magically opened. It was NOT there when I went to "Edit Individual Documents".
I know how to turn the $$%@^ thing off - what I want to know is how to keep it from turning on in the first place. There has to be a "kill" switch somewhere, and if I need to go spelunking around the registry, I can do that.
This is happening on a brand-new Win 7 64 bit laptop from the first time I opened the document. It was also doing this in my former laptop, also Win7 64 bit.
thanks!