Unable to sort dates in Excel on new PC

[freebird795]

Hope somebody can help as this is driving me doolally-tap.

We have an access database at work which produces reports in Excel; install dates, closure dates, etc.

Everything worked fine until last week when I received a new laptop. Since then I cannot sort things by date, unless I convert them to values, etc.

A typical 'sorted' list looks like this:
01/12/2014


03/11/2014
03/12/2014
05/01/2015
08/12/2014
18/08/2014
Everybody else can sort them correctly. Nothing has changed on the database or any of the templates that we use. It would appear to be something on my copy of Excel. I've gone through the menus and options and can't find anything.

Any help is much appreciated.