View state

1. Create an .aspx page, and then add a Button server control to the page.
2. Use the following URL to open the page in your browser:

   http://localhost/myweb/page.aspx

3. Modify the .aspx page so that the page is recompiled.
4. Open a new instance of the browser.
5. Use the following URL (notice the difference in the capitalization of "myweb") to open the page in the new instance of the browser:

   http://localhost/MyWeb/page.aspx

6. Return to the original instance of the browser, and then click Submit. Notice that you receive the error message that is listed in the "Symptoms" section.

My god Mart in your last post you are just reproduce the bug ??? They give us those 6 steps to show us how to reproduce the behavior. Look in the RESOLUTION section instead:

RESOLUTION

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix...

http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTA CTMS

Like i said before, usually this bug only occurs on production server that's why you see localhost in the Steps to Reproduce the Behavior section. But if you have that bug with your hosting provider, like Diep-Vriezer said, you better ask them to update to framework 1.1 or leave