Hi markib,
Thanks for your post and apologies to hear you've been having an issue with the TV Anywhere website not recognising your device.
Whenever you update your browser or OS then the device would need to be re-registered. I have gone in to your account today and added a device change for you.
Using a PC/Laptop go to anywhere.virginmedia.com > My Profile > Device Settings. Remove the PC registration by clicking on the Delete button. Once you've done this, using the device you are trying to re-register, open up the TV Anywhere site again and log in. Try to stream Channel 4 and this should then prompt you to register the device.
Follow the prompts and this will register the device for you and streaming will then commence
Has this resolved things or do you still get that error?
Come back and let me know.
Thanks,