unhandled exception error

[nisrinee51]

When I run my ASP application, it gives me this error anyone had an idea why it does that. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.InvalidOperationException: Collection was modified; enumeration operation may not execute. 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.