CLR Stored Procedure - Directory.Exists always returns false

Hi
I have a CLR stored procedure which has been working fine for over a year. I'm now moving it onto a new server and it has stopped working.
I'm debugging it on my local machine now and the problem with it is when it get to a line in the code which checks if a directory exists. Whenever it gets to the Directory.Exists line, its always returns false.
The directory definitly exists, I've tried changing the strpath to C:\Windows and it still returns false.
I've think its a permissions issue but I'm not sure what permissions to add. I've given the ASPNET user permissions to the directory but it didnt make any differnce. Are there other permissions that I need to set up?
My code is below.
Any help to greatly appreciated.
if(Directory< ...