On my guild's website (ibr.dkpsystem.com) we use the raid analysis ability to determine raid attendance over the last 30 days (which we use to create member ranks). The website's time zone (server time) is -6:00. My local time is -5:00 so I have my account set to that time. My GM's time zone is -7:00. He noticed that he and I had different numbers for the %s over the last 30 days. The time period we were looking at was 11/02/07 to 12/02/07. I showed 118 raids in that time period (look at character Remmz, as he has 100% attendance). My GM was showing 116 raids in that time period. When I temporarily changed my own account's time zone to -6:00 I too saw 116 raids.
The difference in the hour between CST and EST was making the website no longer "see" the two raids that occurred on 11/02/07. They occurred at 21:01 and 22:01 CST (-6:00). We can't figure out why the shift of one hour would cause the website to effectively only show 11/03/07 to 11/02/07 instead of the dates we requested.
Any insight would be appreciated. We know how to work around the problem, but to have the site work correctly would be easier and less confusing to our members... for whom a rank, and therefor invites to raids, may be effected by missed day in the raid analysis.