I have a problem. I was doing some plotting of result with embedded charts
(approx 10 xy-plots) in a sheet. When I save the workbook the first time
there are no problem, but whenever I open it the second time (and save it
again) the filesize goes from 100KB to 30MB. without changing anything!

Try opening the file:
http://home.tiscali.dk/phreaky/excel/titrations.xls

And save it in a new filename. Why is this happening? how do I neglect the
problem?

NO the file does not have any macro/vira or anything.. only some raw data in
sheet1 and some embedded charts of the data.

--
Philip