new orders going into Missing and marked as Cancelled

Hi I am using latest OC, with Paypal Payments Standard.

I am not in Test mode or Sandbox.

Any new orders received are going into Missing and marked as Cancelled. Also nothing shows on Customers Account History.

I see this has been a much reported problem going back years but I don't see any straight forward fixes?

Can anyone suggest what is going on here.

just to post an update, I have tried absolutely every possible suggestion so far, and now have spoken to Hostgator who say..

Lakedra G thanks for your patience, PayPal did release a statement requiring upgrades to SSL certificates from SHA-1 to SHA-2 data encryption algorithm and this was the first thing that I checked........... but the ssl is compliant as defined

Lakedra G have you had your developer take a look at the coding for this service? we cannot diagnose these for you and a developer will have to look into the coding unless there is a script or error message indicating an issue on the server

So is this a Coding Issue?????

I am at my wits end here!

Did you check that you have the orders status set correctly in the paypal module? It is under Paypal standard > order status tab.

Yes that was all set correctly, still no answers found.