Visual Tab / Editor not working.

I’m having an issue were the ‘Visual Tab’ is not displaying anything.

I’m drawing a blanks, I’ve searched Google and various other sites and the conclusion is I’ve had to do a few things, so following various steps, I’ve tried the follow :-

Disable Plugins – All Disabled – Still same issue.
Use Default Theme – Used Twenty Thirteen, Twenty Fourteen and Twenty Fifteen, with and with all plugins disabled – Still same issue.
Tried Different Browsers – Firefox V34- IE 11, Chrome V39 – Still same issue.
Deleted all Cache and Cookies on all browsers – Still same issue.
Personal Profile – ‘Disable the Visual Editor when writting’ checked, unchecked, before and after default themes, current theme, etc

Java is up to date (not that I know if that affects it)
Flash is up to date, but like Java, I don’t think that is an issue.
Windows is upto date (Windows 8.1)

All possible combinations of the above have been tried, and yet, I can’t get anything to appear in the Visual Tab

Can anybody else help me? or suggest something else I can try, before pulling my site down?