Disappearing party members

Time:12:43 A.M 9/26/2013
Frequency: The whole instance
World name:Behemoth
Character name:Kheima Rayne
NPC name:fellow PC
Monster name: N/A
Class/Level:SCH 36
Party or solo:Light Party
In-game time:N/A
Area and coordinates:Braflox Longstop
Steps:
1.Tank disappeared on my screen but was still in the instance. (other members could see him)
2.Could not target him when this happened even when scrolling thru the party list.
3.the instance was bugging ever time he died. Couldn't finish because I'm the healer that couldn't target the tank.
<*Add more steps if necessary>

Connection Specs
- Type of internet connection/provider AT&T U-verse
- Modem maker/model number N/A ATT?

Model Number of the PlayStation 3 You Are Using
- Model Number: