New virtual machine cannot access it's virtual hard disk

[simonfbroad]

Running Virtual Box version 4.3.6 on Windows 7.
Created a new virtual machine (Windows XP) and virtual hard drive, in qcow format.
In the VirtualBox Manager console, under Storage, it says "IDE Primary Master: NewXpMachine.qcow (Normal, Inaccessible)"

If I shutdown and restart VirtualBox I get a popup warning that says "One or more virtual hard disks, CD/DVD or floppy disk image files are not currently accessible......."

Have tried this more than once than once.
I have checked that the file shown in Virtual Media Manager exists in the location given, and that my current user id has full control over the file,

Don't know where else to look, would be grateful for any ideas.

Simon.

[JN]

I've got the same problem. Did you ever find a solution?

[mpack]

Why qcow format? The best format in a VirtualBox VM is VDI.