Error when attaching workflows to Sharepoint 2010 lists

Question

Hi,
I am getting an error when trying to attach an approval workflow to any SharePoint 2010 list on my development server. From the below error in the log I remember that I got this
same error in Sharepoint 2007 MOSS. It occurs because I have underscores in the server name. I know that I can get around this by either changing the server name or using alternative access mappings to access the server without the underscores. Does anyone
know of a way to fix this so that the srever name can have underscores which I believe are viable characters in a server name.
System.ArgumentNullException: Value cannot be null.  Parameter name: g    at System.Guid..ctor(String g)     at Microsoft.Office.Workflow.WrkAssocPage.AssociationOnLoad(EventArgs
ea)     at Microsoft.Office.Workflow.CstWrkflIPPage.OnLoad(EventArgs ea)     at System.Web.UI.Control.LoadRecursive()     at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint,
Boolean includeStagesAfterAsyncPoint) b06aa203-3cbe-4180-806a-4ed994fbbee9

Answer 1

I think you are referring to the following KB about special characters. 
http://support.microsoft.com/kb/905231
This is not the reason we are experiencing the workflow problem though.  It is related to Internet Explorer security which changed.
Issues after you install updates to Internet Explorer or Windows
http://support.microsoft.com/kb/325192
"Cookies on ASP pages are blocked if the server name contains characters that are not supported by Domain Name System (DNS). For example, you cannot use underscore characters (_) in the server name. This behavior is by design."
Resolutions include:
Removing underscore from server name
Use Alternate Access Mappings
Extend and map using a web application that uses a URL path that does not use the servername
Decrease the security level in IE on the Security tab (not recommended)
Uncomment a line in the web.config which is commented by default (not recommended)
<add name="Session" type="System.Web.SessionState.SessionStateModule" />
Hope this makes the issue more clear.  I have updated the SharePoint KB to point to the Internet Explorer KB so people will be aware that the IE change does affect SharePoint behavior.  This is not a SharePoint issue however.
Fred Ellis - MSFT