Health Monitoring reports “Invalid ViewState”

One problem we have been encountering for nearly a year is a problem which reports ASP.NET errors, but actually does not cause any problems for the user. The error looks like this: ** Events ** --------------- Event code: 3005 Event message: An unhandled exception has occurred. Event time: 3/23/2010 11:44:44 AM Event time (UTC): 3/23/2010 11:44:44 AM Event ID: 6be66d016f1e43b48adbd638e202c698 Event sequence: 3548 Event occurrence: 1 Event detail code: 0 Process information: Process ID: 7872 Process name: aspnet_wp.exe Account name: WEBSITE\ASPNET Exception informat... [More]