I got this today when trying to display who was online in my linkshell at the time and an error which kicked me off the game occurred. I know there was another topic on it but it seems to be locked.

Platform: Windows Vista
ISP: AT&T
Connection: DSL
Time: April 7th 2011, around 10 pm
Frequency: Once, first time this happened to me
Character: Hotohori Ryu
Race: Hyur, Highlander
World: Saronia
Area: Uldah, around the adventure guild but I wasn't lagging
Steps:
1) Go Menu > Linkshell > Display Members
2) White box pops saying "An error has occurred. Please restart Final Fantasy XIV"
3) Click okay in the white box and the game shut down completely