Invalid viewstate w/Mac OS

[Guest]

Hello,

I am having a very strange issue regarding our macintosh users running IE.
For some reason some users running IE on the Mac are getting an invalid
viewstate exception when first coming to our site.

When first time users come to the site they are redirected to a select
location page where they need to select a country so we can show them proper
pricing. However, users on the Mac seem to have issues during the redirect
back to the homepage after selecting their country. I've read that using
Server.Transfer can cause this in some scenarios but I'm simply doing a
Response.Redirect.

I have gone as far as implementing this solution but it didn't work either.
The error message just changed since it couldn't find the VIEWSTATE0 object.

http://weblogs.asp.net/pwilson/archive/2003/08/21/24867.aspx

I have a couple Mac's in-house and can't recreate the problem at all. The
site runs great for Safari users and everyone else for that matter but not
the IE / Mac users.

Here is one of the exceptions:

Error Message
System.Web.HttpException: Invalid_Viewstate
Client IP: 128.135.77.47
Port: 49369
User-Agent: Mozilla/4.0 (compatible; MSIE 5.23; Mac_PowerPC)
ViewState: dDwtMTYyODAxNjUyNDt0PDtsPGk8MD47PjtsPHQ8O2w...{removed for
brevity}...UuanBnOz4+Oz47Oz47Pj47Pj47bDxpYkdvOz4+CNQmNVO7uuNE1azvcGx8rovqWBA=
Http-Referer:
http://www.dharmacon.com/SelectLocation.aspx?ReturnUrl=/Default.aspx
Path: /Default.aspx. ---> System.Web.HttpException: Authentication of
viewstate failed. 1) If this is a cluster, edit configuration so all servers
use the same validationKey and validation algorithm. AutoGenerate cannot be
used in a cluster. 2) Viewstate can only be posted back to the same page.
3) The viewstate for this page might be corrupted. --->
System.Web.HttpException: Unable to validate data.
at System.Web.Configuration.MachineKey.GetDecodedData(Byte[] buf, Byte[]
modifier, Int32 start, Int32 length, Int32& dataLength)
at System.Web.UI.LosFormatter.Deserialize(String input)
--- End of inner exception stack trace ---
at System.Web.UI.LosFormatter.Deserialize(String input)
at System.Web.UI.Page.LoadPageStateFromPersistenceMedium()
--- End of inner exception stack trace ---
at System.Web.UI.Page.LoadPageStateFromPersistenceMedium()
at System.Web.UI.Page.LoadPageViewState()
at System.Web.UI.Page.ProcessRequestMain()


Thank you for any insight you can provide.