Sorry for the delay in any responses. I don't use Vista or Office 2007, so my own suggestion is limited.
Does this user have any Add-ons for his Office Word and Outlook applications? If so, perhaps he could uninstall those and see if that changes the display back.
Before that, did he try Vista's System Restore? It may be known differently in Vista than it is in XP.
If neither works, and no-one else here responds, I would re-post in our Vista forum here;
I do a lot of troubleshooting for friends and family, and have seen a huge scope of problems and maladies. This one, however, has me completely stumped.
From what he told me, he simply launched Outlook as usual, but was met with a different appearance. The background is white, the images and buttons are like, 2 pixles each, and the interface is made largly of black and white. I opened Word to see if it was a problem only in Outlook, but the Office button was pixelated, the ribbon was white, and it looked like a classic theme of some variety had been applied.
I checked the Office Options, and theme settings are still set to the default blue. The rest of the operating system is looking like it always has, with all visual effects except aero glass, which had been turned off earlier.
The computer is running Vista Home Premium x86, with Office 2007 Small Business. Everything is properly activated and functional.
Any help on this would be great. He says it does not interfere with functionality, but it is stuck in my mind now.