I am currently developing a silverlight application, however yesterday I started getting the following error message every time I run the project:

I am a little confused as to why I am getting this message, and am looking for some help to track down the cause. If I click “yes” to debug – nothing happens. Also, I have no Line 1805 in any of my source files!
This error message started appearing yesterday, and appears as soon as I run the project, shortly before the first page loads. If i click yes or no, the project then loads and runs perfectly, I cannot see any unwanted behaviour.
I have been using source control, so I rolled back the project to a point before the error started appearing, however I am still getting the error!
Could it be a setting in VS Web Developer Express 2010 that I have accidentally changed?
Thanks for the answer Anthony, however I just solved the issue.
I cleared the browser cache, and now the error has gone away. How bizarre!