I only use Developer Express 3rd party assemblies so I wrote them also.
Here is the response:
"We use a certificate from Thawte to codesign all our assemblies. We
used to just use strong keys, but recently a customer (Microsoft) asked
us to codesign our runtimes so their IT department can deploy an
application built using our products across their company. Apparently
our competition do this, so we were glad to apply for the certificate
and start signing our components. It guarrantees that they have not
been altered since we shipped them.
But it seems like your system keeps asking thawte if the same Developer
Express (we have only one) certificate is valid. I am not sure if this
started happenening because your systems security scheme changed or if
you just recently downloaded a version with codesigned assemblies.
I understand you can import the certificate into your trusted list and
it will stop having to ask the thawte root authority over and over.
Feel free to email our team (e-mail address removed) with any questions
you may have about the process - they will be glad to help and possibly
create a knowledgebase article on the process.
rgds,
Richard Morris
Developer Express"