I have a problem with XLSX-Files. It can be reproduced in the following way.
I have an Excel-File with coloured and not coloured columns. I save it from Excel2007 as xls and also as XLSX (Office 2007 format). If I open the xls-File with PaintCell demo it looks like that:

If I open the xlsx-File with PaintCell demo it looks like that:

With xlsx I also get the message "There are unknown values". But the debug file in "d:\xtemp\vals.txt" only shows baseColWidth and no information, where the unknown values have been.
What can be the reason for that?
How can this bug be removed?
Yours sincerely
Peter