I've this machine which has Office 2003 installed with Compatibility Pack. User received one file which she has to work with in XLSX format (file has to stay in that format so options to save it as XLS can be skipped). When she opens the file from Desktop or any other location it gives an error like "Cannot find the file in following location" and in the background it starts Converting XLSX file to XLS. In the end Excel is opened up with some random file name X000008.xls (Read Only) which is just 1 to 1 conversion of the XLSX document.

However if I go directly to Excel and use File / Open and try to open the XLSX file no error or conversion is done. The file is writable and can be saved in XLSX format.

The file name is simple like This_file something.XLSX, I've even tried to remove all spaces but it gave no better results.

Anyone has any recommendations?

So far I have done: 1. Uninstalled Compatibility Pack and installed it again. Tried opening it without any other updates and the error still pops out.

In progress:

1. I am now running all possible updates of office (like 5 of them) which i suppos won't fix anything (as they were applied when I've uninstalled compatibility pack).
2. Next in run will be (not yet done) installing Windows XP SP3.

What other things I can do?