Running SharePoint 2010 Server running on Windows 2008 R2, Virtual Machine
On the application event…following error even keep on comming…Load control template file /_controltemplates/TaxonomyPicker.ascx failed:
Resolution
Locate the file “TaxonomyPicker.ascx” in the Controltemplates directory of the C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\TEMPLATE\CONTROL TEMPLATES\ and search for the following line Control className="TaxonomyPickerControl" .... locate ‘,’
and replace ‘,’ with ‘,’... and then save the file. This will resolve the error.
PREMNAIR'S Blog 
the error does come back though…
see update to this fix (look for section in orange) here: http://todd-carter.com/post/2010/05/03/Help-Wanted-Taxonomy-Picker.aspx
I too had this error and struggled to solve it. But your post gave me solution. Thanks for it.
http://godwinsblog.cdtech.in/2010/12/sharepoint-2010-root-of-certificate.html