Odd Reciever Problem with DTS

[Moose1132]

So I recently found out that my reciever is slightly delayed with the audio whenever I'm playing something in DTS (like someone's mouth will move and then a second later I'll hear what they said). The catch is, that it only delays when I'm using the reciever through an optical connection (which is all the time now) and only with DTS. The reciever is an upconverting DVD player so I used that before I got my PS3. I also know it's not the PS3 since I have the same problem with the optical connected to a 360. The reciever is almost 2 years old and is an LG if that helps. Any ideas on how I can fix this or is it just messed up?