Excel Sheet takes forever to save

I have an Excel Spreadsheet with a lot of formulas and define names. It is around 9MB. It was saving at a normal speed. Then all of the sudden it is taking 15 to 20 minutes to save. It is slowing down so much that it is timing out.

Does anyone have a suggestion on debugging this? Is this a common problem for Excel 2007? Is there a way to speed it up?

My IT guy doesn't know what the problem is but he says he has an Excel spreadsheet that is 250MB and it doesn't take him that long to save it.

Any help is appreciated.