Virtual Machine Manager

The VMM Admin console crashes because the VMM service crashed
In System Center Virtual Machine Manager 2008, if the Job Count exceeds the recommended upper limit then the Virtual Machine Manager service may consume a large amount of memory or exhibit high CPU utilization.

Adding a Hyper-V host in VMM fails
Microsoft Knowledge Base article 2584907 can help troubleshoot common errors that are logged in the VMM Administrator Console when an “Add virtual machine host” job fails. The errors include 2912, 2916 or 2927 and can be due to issues with WMI or WinRM, duplicate SPNs, corrupted performance counters, or firewall configurations.

Creating a virtual machine fails (1)
This issue can occur if the port used by BITS to perform file transfers is in use by another application or service. BITS uses a default port of 443 (decimal) which is commonly used by secure web sites (HTTPS).