Resolving an irritating "Invalid class string" with Win7 PRO and Word 2007 with customised Quick Access Toolbar

This issue has not occured for me on WinXP PRO/Word 2003 or Win7 Home Premium / Word 2007; only with Win7 PRO and Word 2007 after updating to X2.0.4 (Build 4459).

After this upgrade I could still insert a reference but I could not edit it using the button I had added on the Quick Access Toolbar due to “Invalid class string.”

The suggested fix at did not work.

After several fruitless hours uninstalling Endnote, setting my account as Administrator, then re-installing Endnote and updating to X2.0.4 - it still did not work.

However, by accident I found that if I used the Edit Citation button on the Endnote 2 tab - it worked!!!

The solution was to remove the button I had added to the Quick Access bar, and re-add it.