'Object reference not set to an instance of an object' when attempting to view published website.

Hi,
 
I have been developing an asp web site in VS2005, which builds and runs fine from the development environment. However when i publish it to a local test directory (Inetpub/wwwroot/TFL1617) and attempt to view it i get the above error and the following:
 Source Error:





An unhandled exception was generated during the execution of the
current web request. Information regarding the origin and location of the
exception can be identified using the exception stack trace below.

Stack Trace:





[NullReferenceException: Object reference not set to an instance of an object.]
System.Web.Hosting.ISAPIWorkerRequestInProc.GetServerVariable(String name) +1841
System.Web.Hosting.ISAPIWorker ...