Thanks for the feedback, glad to here it worked. What we actually did is to get rid of any suspend files etc. by moving all unneeded files to the Backup folder and by consolidating the system disk. maybe deleting the .vmss and some other files might have helped too, but this way the whole folder is clean now.
What you could still consider is to consolidate the "data" disk. However, this requires temporary disk space (~260GB) and - with an external USB disk - it might take some time (unless it's USB3). If you like to do this let me know and I will provide more details.
André.