Most often, the problems with opening the files created in Excel, due to the fact that they were created in different versions of the program. If the file was made in Excel 2007, 2010 and 2013, it is unlikely to be properly opened in older versions of the program. The problem can be solved by installing a special patch created specifically to solve these compatibility issues. It's called "compatibility Pack Microsoft Office for file formats Word, Excel, and PowerPoint 2007". Let the name and the figure sounds 2007, but the difference between the files created in Excel 2010 and 2013 there, so this patch is suitable for solving problems with opening files.
There is a free program that functionality is not inferior to Microsoft Office and in particular Excel Microsfot. It's called OpenOffice.
If you install this patch for Excel 2003 is not possible, you can ask to re-save this file from the new format ("xlsx") in the older (xls). In order to do this, Microsoft Excel 2007, 2010 or 201 you should click "File" then click on "Save as", then choose from the offered formats is required.
Formula and editing
Microsoft Excel 2007, 2010 and 2013 have a number of significant advantages over older versions. First, is the protection of cyclic formulas. It is a logical fallacy, in which the loop is embedded in the formula will be endlessly repeated. In older versions of Excel, this formula could lead to data loss and system lockup at all. More recent versions of the product from Microsoft may block the occurrence of similar formulas, such files cannot be opened in Excel later. If the file to open need, you will have to ask the Creator to remove all cyclic formula from a file.
The file created in newer versions of Excel may not correctly open only when there is a special patch, but with the support of all the fonts with which to create the file. Otherwise, you will have to learn their names and to download from Microsoft official website.
It is worth saying that in Microsoft Excel 2007,2010 and 2013, there are formulas that will not be supported in older versions. Such a file may be opened in them, but the formulas will work not all.
The programs that create files for Excel
At the moment the option of saving the file in xls and xlsx formats offers a variety of programs. Some do it worse, some better. For example, the famous FineReader program is able to scan files directly in Excel format in pretty good quality. These files will be safely opened in any version of Microsoft Excel. But there are many other programs that are not able to do it with the same quality. It can be as analogues FineReader and program, specializing in converting files from format to format. Files created in these programs can be opened in Microsoft Excel with good quality.