Okay - we had a quick investigation of this (end of day here, so quite a few of the team have headed home already).
It seems that in the end-of-week guild-war processing job, an error occurred for a small number of guilds (unfortunately most of the guilds in the top bracket were affected, since the error occurred soon after daily reset), where they got processed twice.
This error was ONLY related to recording players' points from the previous week. Which means 2 things:
1. All players in the Guild will show ZERO points as their personal tally for last week.
2. The internal GW Rankings for players in those guilds will not have been updated, and will have remained the same as week #1.
At first glance, I'm not sure we can fix this reliably THIS WEEK (it will obviously be fixed for NEXT week's update though).
We'll know more tomorrow.
However, if we CAN'T fix it, we'll make sure everyone in the affected Guilds gets a nice little present as compensation.