I encounter the same issue with IE8. I suspect that the web site exemple http://dotnetdate.com/CuteSoft_Client/CuteChat/Channel.Aspx?Place=Lobby-2 is not based on the same version than mine. I use the 5.1.0.0 release.
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Webpage error details
User Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0; SLCC1; .NET CLR 2.0.50727; .NET CLR 1.1.4322; .NET CLR 3.5.21022; InfoPath.2; MS-RTC LM 8; .NET CLR 3.5.30729; .NET CLR 3.0.30618)
Timestamp: Mon, 27 Apr 2009 19:17:43 UTC
Message: Invalid number of parameters.
Line: 627
Char: 67955
Code: 0