Hard to tell if this is a hardware problem with the drive or some application trying to scan the drive. Two things you could check. First, make sure Windows drive indexing is not trying to scan your optical drive. Second, make sure your security software is not trying to scan this drive.
If both of those are ok, I would call Dell and ask tech support for help.
It sounds like some software (whether it's Windows, etc.) is trying to access / look for data on that drive. Can you correlate the time this happens to any software application that may be running, even if its in the background? The light would blink, meaning the optical drive is being accessed, even if there isn't a disk in the drive.
Have you tried inserting a disk into the drive and then removing it? See if that "resets" the drive. If not, you can try removing the optical drive and then putting it back in to reseat it. Not really sure that is the issue but you can try it. Here is a link to the online manual for the Inspiron 3543. On page 18 you can find information on how to remove / replace the optical drives.
Honestly though, to me it seems like some software is trying to access some data, and for some reason thinks that data is on your optical drive and not your hard drive. Perhaps some software or games you installed off a DVD or CD?