So, I've never heard this sound before today. Granted, in my usual lappy setting (my office and home), it's a bit more noisy than it is in my present location (I'm out of town, atm) so it may have been making this sound since the beginning and I wouldn't know it, but... The lappy is the one in my sig (Rev.E 17" PB stock except for 2GB of crucial ram that I installed about a month ago). The sound it makes is a faint, tinny (or nasal-ish, i know it's a weird description) "beep." It doesn't do it more than once at a time, nor does it seem to be following any sort of pattern based on my actions or the time. It seems to be from under the keyboard in the middle. I already thought of iCal alarms, but I've never used the "To Do" event alarms in iCal. I just use the regular calendar features. I'm not too concerned yet, as it seems not to be accompanied by any odd or performance-impairing behavior; however, I would like to see if anyone else has experienced this and what it may be. Thanks a bunch for the help!