I have had something like that happen when charging certain lipos with my old Hyperion EOS7i. It charged fine right up until the cells get close to ~4.1v/cell, then would display an "output voltage too high" error message.

The only way it would work is if I decreased the charge rate to something like 3.3A when it got near that point (on this charger, you can adjust the current on the fly). This only happened on lipos whose internal resistance is kinda high, but won't mention the brand. All of my newer lipos work fine.

Not sure if this is similar to what you are getting...