Let's say someone dropped this new application in your lap called Hyper-V (which rocks by the way). They give you an already built, base image that's in the form of a .vhd file; this will be used when building new images for your virtual environment.
When using the "New Virtual Machine Wizard" to build a new server off that base image.vhd file you may see the following error message when it starts if the read-only attribute on the file is set.
"The server encountered an error while starting (server name here). Please try to re-start this virtual machines after the problem fixed". Also "Attachment "(filename.vhd)" is read only. Please provide read/write access to the attachment. Error: "General access denied error".
This is typically caused because that base image file you are trying to use is set to read only. To fix this right-click the file and uncheck the Read-only box, press ok and start the image by using he Hyper V Manager and you should be good to go..!
Thanks – Kris Wagner, SharePoint Server MVP