It is plain simple. When working for school, I often need —because those dunces in school won't upgrade— to convert my .docx files to the standard 97-2003 .doc extension. However, my converted files are always saved as an upper-case .DOC file rather than the standard lower-case .doc.
I've seen this issue bringing text formatting issues as well as the files not being recognized whilst in Windows Explorer. The files are described as ".DOC files" instead of "Word 97-2003 Text file" or something similar.
I first noticed this on my previous installation on Windows Vista, where Office 2007 was just simply installed using the "Quick Install" option. Same happens here on my new Windows 7 installation. I have not fiddled with the register nor Office's settings in any way and would like to know what it is that is bugging me.
I have, thusfar, not installed Office 2007 SP2 or any supplemental updates due to being on a temporal smallband-connection (yes, we have those disgraceful download limitations here in Belgium).
I changed the extension of one of my Word 97-2003 docs to .DOC and it's still recognized as a Microsoft Office Word 97 - 2003 Document.
It's good that your system does but my doesn't. It can —of course— be opened with Office but often, the text or formatting is messed up.
Even better, Win7 does not display the standard "Word icon", it's a white sheet (as in an unknown filetype) with the logo of Office 2007 on top of it. It's not that important, really but I'm not able to hand in my homework because of the .DOC error.