Using Excel 2003 on a Windows XP machine.

I create a web page each week from a new Excel worksheet, which is named
lastweek.xls. The web page is always named lastweeknum.htm

However, for some reason, when I "Save as web page" to create
lastweeknum.htm, the file appears to get appended onto the previous week's
file.

This began happening after a co-worked tried to "fix the process" by
fiddling around with macros. However, she did that on a different computer
altogether, and the spreadsheet itself is made completely from scratch each
week.

So, something has to be hanging around somewhere causing this append
process, but I can't find it anywhere.

Ideas?