Virtual box - xp sp3 - iis - net 3.5 sp1 - ie8 - using localhost as address

imidditaly after finishing install i tried to login to the new forum.
i get a javascript error and login does not proccessed.
this is the javascript error:

Webpage error details

User Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)
Timestamp: Sat, 22 May 2010 15:03:56 UTC


Message: Sys.WebForms.PageRequestManagerParserErrorException: The message received from the server could not be parsed. Common causes for this error are when the response is modified by calls to Response.Write(), response filters, HttpModules, or server trace is enabled.
Details: Error parsing near '
Line: 4723
Char: 21
Code: 0
URI: http://localhost/ScriptResource.axd?d=aVfUfN6_uFdco9YigilSnzTvYzDRu1mh4PBWs9CSihTYMdMzWMgjKiaF5DjBfRhD7ssTHr_l0_ydG4c2cHfWkzYdyoHl70oKEidoPjkJ1tw1&t=ffffffff862b7db3