iOS 5.1.1 | "Unable to Download Application" | Help Needed

Hi all,

I have been experiencing an issue for quite some time now, I have been getting a notification on my iPhone 4S when I try to download apps from the App Store. I am currently running iOS 5.1.1 (As far as I can remember, this did not happen prior to this software update). The message says "Unable to Download Application" and gives me the option to click "Done" or "Retry"... If I was to press "Retry" the same error message would appear again, and again, and again.

This is a consistant problem, which occurs every time I purchase an app from the App Store. I has got to the point now, where it has stopped being a "nuisence" if you will... but it has become very disheartening and extremely frustrating.

Generally, once I tap the retry button repeatedly, the app will eventually download. However in some cases, I have to leave my iPhone for a period of time, and retry the download and installation process all over again.

I have had my iPhone since December 2011, and have had no problems with downloading and installing apps prior to 5.1.1.

The apps in which I try to install are not of large file size, therefore do not need to be downloaded through iTunes on my PC, and should be able to be downloaded through my iPhone with no trouble.

Any help would be very much appreciated,

Thank you