Yes S.SubZero, clearly a problem. I have however managed to correct it but I am still completely in the dark as to what caused it.
After re indexing the HD etc, etc I did not think to Get Info again, was just looking at the bar graph in About this Mac but as soon as I closed the About this Mac window and tried Get Info again the storage reading returned to normal. So back to the About this Mac window again and all normal, phew!
I did have to erase and reselect a drive for Time Machine as it simply would not advance past "Preparing Backup" but now full backup complete and all well.
It's times like these that I am so thankful for the CCC bootable backup.
Still I cannot understand what caused it other than a utility I am trialling which downloaded last week called iStat menus. It is the later version of Menu Meters a utility I had years ago.
It does have a memory reading as well as core temp, CPU activity, upload/download speed ect but I have been running it for a week with no issues before yesterday.
I think repairing permissions and re indexing did the trick in the end so I hope my experience may be of value to someone else.
Incidentally I live in Bali Indonesia, no Apple Genius Bars here, not even a licensed reseller so we are on our own.;D