[squid-users] squid error for aspx website

Do you have any idea why this error comes out when it passes thru the squid,
I tried to bypass it from squid and it did not have such error and i was
able to submit the next page.
Bobby

www.sms.ac/registration/registration.aspx

Server Error in '/Registration' Application.

The viewstate is invalid for this page and might be corrupted.
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.Web.HttpException: The viewstate is invalid for
this page and might be corrupted.
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:

[HttpException (0x80004005): The viewstate is invalid for this page and
might be corrupted.]
System.Web.UI.Page.LoadPageStateFromPersistenceMedium() +150
System.Web.UI.Page.LoadPageViewState() +18
System.Web.UI.Page.ProcessRequestMain() +423
Received on Tue Jul 06 2004 - 19:08:04 MDT