Thanks to all. First, logging off then on again doesn't do the trick.
Second, the 'fix' on the Kodak site is their own software which works but is bulky; I prefer the MS built-in facility in XP so uninstalled Kodak's. According to the Kodak site, XP's software should work OK with the DC280.
When the camera is connected to the USB it shows up in Device Manager and Explorer; it just won't launch the Get Pictures wizard. I discovered, though, that if in Device Manager I right-click and disable the camera while it's still connected and switched on, then enable it again, up pops the wizard.
Maybe I'll have to live with this glitch. But if any bright sparks out there can shed any light on it, I'm keen to hear from you.