Terribly slow excelsheet!

Hi,

For working out a way of reporting, we've made some simple things in Excel. We work with a way to show up pictures with 'naming' and refere it to some simple pic's. Now if you, for exmple, dot this:
- take sheet 'BMO'
- scroll to the financial section(from row 30);
- change cell G37 to '700'
-> now it really takes minutes before you can do something. It has to do with the 'green triangles in the upperleftside of the cell.

Can somebody say what is going wrong? And how to speed it up?

Thanks!!


NB We use this in Excel '07