#1 - Dec. 7, 2010, 5:04 a.m.
Blizzard Post
Unfortunately, due to an error, some guilds have been able to gain more experience in the first few hours of Cataclysm than was initially intended. Your guild is one of those affected and as a result, has had the guild rank moved back to level 1. This has been done to all guilds that had this issue.

The reason for this is that guild experience has been intentionally capped at a certain amount a day. Tomorrow you will once again be able to gain experience as normal.

We apologise for any inconvenience this has caused you and your guild. The issue should now be fixed so this will not be a recurring issue.