I ran into some problems, that I thought I would share - with the reason, on one of our Virtual Server 2005 R2 machines, running Windows 2003 R2. We had problems copying files to the machine and recieved Delay Write Failed application popups, and it recorded the following event in the Event Log.

Event Type: ErrorEvent Source: DiskEvent Category: NoneEvent ID: 11Date: 9/26/2006Time: 1:30:05 PMUser: N/AComputer: SERVERDescription:The driver detected a controller error on \Device\Harddisk1.

The reason for this was that the Virtual Server host disk was running out of space and the harddisks were running dynamically expanding virtual disks.