After upgrading from Office 2007 to 2003 on my Vista PC, office documents don't have any icons, but the apps have icons as usual (see Screenshot 1.jpg).
In Default Programs, office documents are set to open with an unknown program (see Screenshot 2.jpg).
For .docx, I changed this unknown program to Microsoft Word, to see if that would fix the problem. It didn't (see Icons.jpg), as the icon for .docx just changed itself to something weird.
Although reinstalling would probably fix it, I use a lot of addons with office, so don't really want to have to reinstall them too. Repairing the installation via Control Panel didn't work.
This is probably an easy fix, I just haven't worked out how to do it yet.