A number of people have asked about the hotfix for the .NET Framework 3.5 SP1 when installing SharePoint 2010, mentioned here under 'Software Requirements': - http://technet.microsoft.com/en-us/library/cc262485.aspx. Typically, you need to separately install one of the hotfixes on this page: - http://archive.msdn.microsoft.com/KB979917/Release/ProjectReleases.aspx?ReleaseId=4033 depending on the server type, i.e. Windows6.1-KB979917-x64.msu (Win7) file for Windows Server 2008 R2. However, service pack 1 for Windows Server 2008 R2 installs this hotfix by default. So no need to separately install it. In fact, if you attempt to separately install the hotfix on a 2008 R2 SP1 server you'll see a message "The update is not applicable to your computer". See here for the hotfixes installed as part of the SP1 install for Server 2008 R2: - http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=269. I downloaded the .XLS file and located the 979917 patch - "
Two issues occur when you deploy an ASP.NET 2.0-based application on a server that is running IIS 7.0 or IIS 7.5 in Integrated mode".