The Windows Server have already been tried restarted. VMware service are running as expected and the services have been restarted:
The server is running Microsoft SQL Server 2008 R2. How should I check this?
I have recently taken over on this installation, but upgrading is certainly on my to-do list. ESXi servers are IBM System x3650 M4 which I first had to firmware upgrade, which is now done. Where can I get the right VMware upgrade file to v. 5.5 for a start?
Have you gone through your event logs to see if you have any errors in there?
Also, try to connect to the V-Center application from the server itself, this'll rule out possible firewall issues.
Event logs first though, there must be something in there to tell us where to look.
Regards
Alex
Where can I get the right VMware upgrade file to v. 5.5 for a start?
You'd need to have a VMWare support login so you can download the version from their site.
Restart your V-center server, also really consider upgrading your VMware to something more recent. 5.1 isn't supported any longer.
Regards
Alex