If you have one of the issues below is time update your VMM 2008 R2 SP1:
Virtual Machine Manager server update (KB2691812)
The VMM service leaks memory when you manage a Windows Server 2008 R2 Hyper-V cluster that has HP Cluster Extension Software (CLX) installed.
Virtual Machine Manager Self-Service Portal update (KB2701207)
The Self-Service Portal may not always display all virtual machines if the self-service user has more than 50 virtual machines assigned to them.
Remember before updating to plan your change carefully.
You can download the files from the article.