ALL my birds have disappeared! Help!

Having moved house about six weeks ago, and having had a variety of birds visiting (I previously entered a post about too many blackbirds) they have now ALL disappeared.  I find this incredibly strange.  They came before the snow etc when the garden was green and weather was ok, came during the snow in droves, and suddenly, the feeders, bird table, hanging feeders and trays etc have all been left untouched.  I've never seen the food left at the end of the day before.  But now it hasn't been touched for two days.  Many birds are around but they're flying over my garden and not even sitting in my trees or bushes any more.

Not one regular: tit, nuthatch, blackbird, robin, chaffinch, wren, starling or even pigeon has come.  Yesterday and today I sat in the window and watched for hours and saw NOTHING land or visit.  I'm worried that something's happened.  I've put out the same food (fruit, raisins, seed mixes, peanuts, meal worms, suet, fat balls etc) but nothing has visited. I don't believe the birds have disappeared because they are flying overhead.

Does anyone have a clue what might have happened?  I'm worried perhaps either something or someone has frightened them all off, or worried I may have poisoned one or caused some sort of infection and 'word has spread' amongst my feathered friends that feeding here is dangerous.  I clean tables etc every week and ground feeders are cleaned daily etc.  What could possibly have happened to have caused such a mass exodus? Not one bird has landed and usually I've got too many to count visiting.  Something must have happened.  Help!