Windows cannot access the specified device, path, file

[hayl]

I bought a new computer with Windows 7 Home Premium 32 bit installed on it. I was working on Pastel Xpress and wanted to back up to a DVD-R Disk. As soon a pressed backup, Pastel shut down and now when i try to open it I get the message "Windows cannot access the specified device, path, or file. You may not have the appropriate permissions to access the item." I have tried changing the permissions (Im the only user though and the administrator". I put the Pastel disk in a ran a repair, same error comes up... I dont know what else to try....
Thanks