> (Q1):
Look at...
support.microsoft.com/default.aspx?scid=http://support.microsoft.com:
80/support/kb/articles/q180/7/36.asp&NoWebContent=1

> (Q2):
You simply cannot use those characters in the name. Try a dash "-"...
20-07-2007, or a short text date  like.... Mon 12th July

> Main puspose: I needed  to save  the worksheets  everyday on the
> same workbook.
You are going to have a LOT of worksheets and it's very likely that you
won't see the date anyway!
Try splitting the workbooks up into week numbers... 7 or 5 sheets per
workbook, with links to each in a main worksheet  or web page.