Selected Virtual Machine is inaccessible

[Andrewm]

I am running VirtualBox 5.2.42 on Windows 10 (I want a 32bit version of Windows 7 and information says I can't run this on a later version) with a Windows 7 VM and a Windows XP VM.
My Windows XP VM is now saying 'Selected Virtual Machine is inaccessible', 'Cannot attach medium 'D etc. VBoxGuestAdditions.iso' 'VBOX_E_OBJECT_IN_USE'. I have found various threads but none help - most say find the vbox file and edit it, but whilst I can find one for Windows 7, I cannot find one for Windows XP. XP appears to be VirtualXP.VHD. I have removed VBoxGuestAdditions.iso in Virtual Media Manager/Optical Discs but this has made no difference - it keeps returning!
Where do I go now?

[Andrewm]

Now found Windows_XP.vbox and deleted <DVDImages> and all seems to work again but do I need to get <DVDImages> back? If so, how?

[mpack]

<DVDImages> is just a recent files list.

[Andrewm]

Thank you - I'll ignore it then.