DataSource Controls :: Cannot Evaluate Expression Error After Converting VS 2003 Web Application To VS 2008?

I recently converted a web application of ours to VS 2008 so that we could upgrade to .net 3.51 framework.

I have been making some changes to the layout, to take advantage of ajax and minimize the amout of data needing to be loaded and the number of postbacks processed.

The problem I am having is when I try to save the data.

The page postback calls a local Sub which reads the form data into local variables and then passes these variables to our assembly.

The primary assembly has 70 parameters which are used to populate one of the tables in our database.

So I have 70 local variables just for this call plus a variable reference to the output of the assembly which contains a property for each of the columns in the associated database record.

There are some additional assemblies called to update other tables so, in all there are 121 locally defined variables in this sub.

Bear in mind that this sub is called from the page load event which has 93 of it's own locally declared variables.

Here is what is happening, when I run the code I am using cdate() to convert the value of a text box to datetime and pass it to my assembly. When doing so it throws a conversion error.

So I created a local datetime variable and converted the value of the control to the datetime and passed the variable to the assembly.

No more error, but the proc did not save the data as it was supposed to.

What I noticed in debugging, on the locals tab, is that every local datetime variable displayed the following message:

Cannot evaluate expression because we are stopped in a place where garbage collection is impossible, possibly because the code of the current method may be optimized

I also noticed that on the watch window the same message would display if I attempted to reference any of the datetime controls on the form.

There are only 3 variables and 3 datetime controls that appear to be affected. the controls are all html input boxes. Every other variable and control on the form behaves normally and I can see their values while debugging, it is just these six that are exhibiting the problem, whats more is that they are not new controls to the form.