IE & Firefox Browsers connected but will not open anything

I have a strange problem that started a few months ago

I am connected to the internet via broadband but neither Firefox nor IE will open any websites or pages. I get the circular green arrow for loading but it just carries on spinning for ever, I dont even get 'page cannot be found' or any other message

I can get round it by turning on my PC for a few minutes and leaving it before opening Firefox. I then have to leave Firefox open for a few minutes without trying to access anything. After about 5 minutes the browser will work as normal. If I dont use the browser for 5 to 10 minutes or so once it's working it will not be able to leave the page I'm on or reload it - I'll just get the spinning arrow for infinity again. Again, I can get around this by opening something streaming - some streaming sites will not hold it open but internet radio always will (unless it crashes when I'm on mute - then the browser will freeze again after about 5 to 10 minutes of inactivity)

Once the browser stops working during a session, it will never work again, even following the above procedures. I have to restart the PC and start again

I have reset IE with no effect

I am using Windows 7, IE 11, 32 bit OS