Odd Macintosh problem... Can you help?

I’ve owned and used Macs since the Quadra. Here is something I’ve never encountered.

OSX 10.5.8
Intel Dore 2 Duo 2.4ghz IMac

When sitting idle, it makes the sound of removing something from the Doc… You know, the “Poof” sound with the icon Poofs into a cloud of smoke after removing it from the Doc.

I haven’t noticed any files deleting, but it has me concerned that something is going on in the background.

It is Teleport sharing a keyboard/mouse with a G5 tower and is networked to a Windows NT machine along with another IMac, Powerbook, and EMac. LogMeIn is used to connect two other Mac Laptops. Happens with LogMeIn turned on or off.

Should I be concerned with this mysterious sound? Restarting has not helped. Have you heard of this before?