Symptoms:
While launching QuickBooks Integeration Manager, the following error occurs,

"Quickbooks found an error when parsing the provided XML text stream"

Cause:
When you uninstall QuickBooks, it doesn't remove all its files from the installation folder.  Hence, when you install another version of QuickBooks for a different country, you are likely to run into this error. For example, if a US version of QuickBooks is installed and then uninstalled, and then a Canadian version is installed, the error would be encountered when working with QuickBooks, either manually or through the Integration Manager.

Resolution:
The solution is to uninstall QuickBooks and manually remove all files from the installation folder (typically, in C:Program Files\Common Files\IntuitQuickBooks) before installing another version of QuickBooks.