Ok, one thing I'd like you to try.
Download the v1.08WW FW file again and unpack it.
Disable any PC security software temporarily. Re-enable after sending the FW file.
Use the following process to go into Recovery mode and use IE11 x32 or FF browser with any security add-ons disabled.
Emergency Recovery ModeSend the v1.08WW .bin file in the recovery mode.
After it loads, using IE11 or FF factory reset the router and set it up from scratch.
Make your reservations up to the limit. When you have reached the limit. Go in and try to remove one or two reservations.
If the problem still happens, I've been told to have you contact D-Link Support Canada and they will help you from here.