This happens quite a lot with my TV6 box which I've only had for over a month now, it seems to happen with various content no matter the content provider and it looks to be caused by the Virgin Media content server refusing connections and i suspect it's due to congestion.
Virgin Media are heavily investing in their network at the moment however this simply means they are laying more cables to connect more people but not actually upgrading their back haul or content servers so the more people they connect the more "400" connection refused error messages we will all start to see.
Make a note of each day you have received the error and if you receive the error more than 10% of the time during your billing period contact Virgin Media to request a partial refund as you are paying for a service which you are not receiving, on demand is a service you pay for the functionality of it is not an "added extra" so don't let them tell you otherwise.
I have experienced the 400 error 6 days out of the 42 i have had the service for so i will shortly be on the phone.
On a side note, i tend to receive it more often when trying to view HD content via on demand and i suspect this will be due to the higher bit rate and network load in order to stream it.
I'm very sorry for the problems you're experiencing in trying to view On Demand lately. I've located your account using your forum profile information to run some tests on the set top box.
We're not detecting any errors from our end at the moment, I hope that means that you're not seeing this error any more? We'll be here to take a closer look if you're still experiencing the issues, just let us know
I have had this error for a few days when trying to use on demand. I'm not even trying to watch a film in HD. Considering how much we pay for this service it's ridiculous. Postcode L23 1TL House number 21