I have a weird situation that I cannot figure out. The code below iterates through all of the worksheets in a workbook (Excel 2007) and takes the sheet name and a link to a particular cell on each sheet. On all my tests everything works perfectly, until the workbook has too many sheets (haven't figured out what the magic number is yet - 20 seems fine.) If there are too many sheets (at least, that is the only thing that I have isolated it down to) then I get an Exception from HRESULT: 0x800A03EC thrown. Any ideas on what is causing this and how to get around it?