When I run my asp.net application on a web farm I get the following error

"The viewstate is invalid for this page and might be corrupted"

Microsoft Knowledge Base artice 323744 talks of this problem and mentions a
hotfix which is not available on the web site.

Has any-one else resolved this problem ?
Does any-one know where I can download the Hotfix from ?
Any Advice on ways around?

Tnx Geri