At this moment in time I don’t have any more Hyper-V clusters to support that are below Windows Server 2008 R2 SP1. That’s good as I only have one list of patches to keep up to date for my own use. As for you guys still taking care of Windows 2008 R2 RTM Hyper-V cluster you might want to take a look at KN article 2135160 FIX: "0x0000009E" Stop error when you host Hyper-V virtual machines in a Windows Server 2008 R2-based failover cluster that was released today. The issue however is (yet again) an underlying C-State issue that already has been fixed in relation to another issue published as KB article 983460 Startup takes a long time on a Windows 7 or Windows Server 2008 R2-based computer that has an Intel Nehalem-EX CPU installed.
And for both Windows Server 2008 R2 RTM and SP1 you might take a look at an MPIO issue that was also published today (you are running Hyper-V on a cluster and your are using MPIO for redundant storage access I bet) KB article 2522766 The MPIO driver fails over all paths incorrectly when a transient single failure occurs in Windows Server 2008 or in Windows Server 2008 R2
It’s time I add a page to this blog for all the fixes related to Hyper-V and Failover Clustering with Windows Server 2008 R2 SP1 for my own reference