I find i only have problem with instances when i am in an instance making that instance.
For example in a guild instance and dont want to wait for repop so i fire up a group instance while in the guild instance 50% of the time the instance is bugged. But if I zone into pub before making the instance I never have any problems.
Hey Funk
Yeah - my success rate on creating a Group Instance in a GI is much less than yours (maybe 20% of the time it works without bugs). It seems the most common problem I have is the zone crashing after about 20 mins or so of play - then when I come back I'm in the nexus and the zone has gone poof! I'm guessing the tech Gods love you more than me at this point
It's funny - after I wrote this post last night and went back into the game I had no problems with any GI. Mind you - I was playing right after the server reboot.
Cheers
Strix