I just upgrated from VS2005 to VS2010 and works fine except for the following error on IE8 only:
User Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0;
.NET CLR 1.1.4322; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729; .NET CLR
2.0.50727; yie8) Timestamp: Tue, 16 Aug 2011 18:46:04 UTC
Message: ASP.NET Ajax client-side framework failed to load.
Line: 130
Char: 34
Code: 0
URI: http://...
Message: 'Sys' is undefined
Line: 15
Char: 1
Seems like the the ScriptResource.axd js is not loaded correctly most of the time on this browser.
I've researched a lot about this kind of error and tried several things without luck. The wreird thing is that it's happenning just on IE8. Chrome and Firefox work fine. It also works fine sometimes on IE8 :S