When I open or try to save an .xls docu, I am getting a message:

Microsoft Excel cannot open or save any more documents because there is not enough available memory or disk space.
* To make more memory available, close workbooks or programs you no longer need.
* To free disk space, delete files you no longer need from the disk you are saving to

I do not have any workbook open, or other program running except IE. There is sufficient space in the disk

Please help