Every time I click on something in the Data Files window, the Object Window or the Cell View Window, my CS makes a "Ding" noise.
I have no idea why it just started doing this, but it's very annoying. Restarting my computer didn't help.

Anyone have this problem before?

No, but I think I know the problem.... Maybe...

Control Panel->Sounds and audio Devices->sounds

Under 'select' at least when I tested it, every time I 'selected' something (on a menu, or just about anything), got an annoying ringing sound. Your sound theme is likely 'blank' as well, meaning someone messed with it recently (A son or daughter perhaps?).

Delete the blank one, and change it to windows default, or no sounds.

Ah, yes. That was it.
Thanks for precise info.

Locked per OP request.