iTunes freezes at sign-out or if closing while signed in

Current version 10.6.0.40 on Windows XP MCE SP3. Every time I sign out of iTunes (used on a shared PC), iTunes freezes but with no error messages. Same thing if I simply close iTunes while signed in. My display gets corrupted and I can free it, and my PC, up again by forcing a shutdown of iTunes via Task Manager. If not signed in, it closes normally.

This behaviour has been occurring for some time, through several version updates. The iTunes Store functions normally while signed in - it's just the freezing at sign-out, or closure while signed in, that is a problem.