1800's date problem

working on a sheet I have one col that is formated for dates (yyyy-mm-dd) this is fine if you enter a date from the 1900's or 2000's but enter a date from the 1800's and it's a no go!

example:
Enter 14 jul 1941 and it formats 1941-07-14 no problem
Enter 14 jul 1841 and you get nothing just 14 jul 1841 no formating at all.

And this is the same for all the date formats...

Any body got any idea how to get round this.
I have over 20,000 lines of information to enter in and 99% of it has a 1800's date.

See here:

http://www.exceluser.com/explore/earlydates.htm

or here for an addin:

http://j-walk.com/ss/excel/files/xdate.htm