Hello Anthony Smith,
Thank you for contacting us.
We had such issue in the 3.6 versions - there is a code in one of the providers, that should fix all links in the content items. The problem here is that this code is run on every application start, rather than just once. The issue is resolved in Sitefinity 3.6SP2 but we will advise you to upgrade to our latest version.
We apologize for the inconvenience.
the Telerik team