I rooted my NSZ-GT1 immediately after opening the box so I don't know if this problem is related to having rooted it or not. Both the GTV Media Player app and GTVBox stutter in the same way when playing back mkv files using DTS. It pretty much always happens. I'm playing them over Twonky 7.0 or the current version of Playback using UPNP on a gigabit wired connection. If I play them on a Boxee Box or WDLive+ they play perfectly. I can't keep the GTV if I can't get it to play mkv files with DTS. I'd un-root right now but I'm concerned about the GTVHacker splash. If it doesn't get replaced by the stock splash, I think Best Buy might not be very happy with me!
Does anybody have a fix for the DTS stuttering or can you assure me that if I manually update it to current firmware the splash will be stock again?