Hi James and David,
I regret for the inconvenience caused.
Could you please check the following kb link?
http://www.syncfusion.com/support/kb/studio/Default.aspx?ToDo=view&questId=35
This kb article will provide the details of why this error occurs and how this can be cleared.
Please change the version number to 4.3.0.xx, in the document, as in your system as this kb can be applied to all of the 4.x versions.
Please try this and let us know if this helps.
Thank you for your interest in Syncfusion products.
Regards,
Nanda