Hi, Karl.
It's likely firmware/SD card related, and eventually will cause a significant problem for you. You'll find the fix in the "Equipment Tips"sticky (Topic: SD CARD RELATED) pinned to the top of the first page of the 2488/DP-24/32/SD forum.
Even though you've been a member for 2 years, if you haven't done so recently, you may also want to read the "New Member" sticky. It's been updated with information many have found useful.