Grey Loading Screen, Products failing to update

Hi
I currently have a issue where i need to update the prices of some products, But every time i go in and change this, a the screen goes grey and the loading bar appears, this doesnt do anything, then disappear if i click again. and the change doesnt take effect.

I have tried leaving it on the loading screen for a hour and on different machines, but still nothing, i was going to create a new item and delete the old but i get the same issue