Unexpected Interactive Services dialog detection

I'm getting an Interactive Services dialog detection message being displayed periodically on a system running Vista Home Premium.

In the notification, clicking Show program details expands the notification box to display

Message Title: Locate File
Program Path: C:\Windows\system32\comdlg32.dll
Received: current date and time

When I click Show me the message, a Locate File dialog box is displayed, with a pre-filled file type of Address matching data file (Address.cas)

I close the dialog box using the Close [x] button, click Return in the notification and return to my desktop.

I've just been closing the notification without displaying the message. I'm concerned that some sort of malware may have slipped past my McAfee security software, even though I've noticed no other ill effects so far.

Does anyone have any ideas about what may be causing this?