Excel cell data corruption

[jamesarley]

I have a spreadsheed of about 20 columns and 6000 lines. I recently added an aditional column to filter by. Each time I return to the spreadsheed the data in the added comumn is corrupted in a few cells. What is causing this?

[FDibbins]

is it giving any sort of error message, like circular error or anything?

[jamesarley]

Thanks for your response.
No error message. When I first correct the sheet, it appears to perform well. But the last column, outside the print area, changes by the next time I open the sheet. I have 4 variables in that column, and on just a few of the lines they change or turn to blank fields. I have an assistant who updates one of the fields, and adds new lines, but she does nothing in the column that is inconsistent.