Might be possible that data is getting corrupted on it's way to the DNS. Anyway for you to isolate a single PC (if you have many) and the DNS on a single router/switch.
I'd suggest:
- resetting the DNS to factory default
- disabling UPnP, iTunes, FTP, etc. during your tests
- using known "good" ethernet cables if yours are home-made
- disabling Jumbo Frames if you're using this feature
- disabling any scanning software on your PC - ex: anti-virus, etc.
The goal is to try and isolate where the corruption is occuring. If it turns out that it is the DNS, it may be possible that it's a hardware connector (backplane) related issue and the unit may need to be serviced.
Keep the folks informed of your discoveries as I am sure other like myself will be very interested in your findings.
HTH,