Lemme tell you about a fun little bug in the TFS Build system. You can create build definitions, you can set the schedule for those builds. You can, for example, schedule builds that run at a certain time of day every day (or every weekday or every Tuesday, or whatever). That build information is then stored in an internal representation which is actually used for scheduling. And that internal representation, it uses UTC times. Can you see the bug here already?
So, your build system will be scheduling daily builds at the same time every day, and then suddenly after a DST change those builds will be an hour off from when you expect them. But here's the even more fun part. If you simply happen to edit and then save one build definition after the DST switch then it'll be saved with a different UTC time (due to the different UTC offset) and it'll run at the correct local time of day.
So, your build system will be scheduling daily builds at the same time every day, and then suddenly after a DST change those builds will be an hour off from when you expect them. But here's the even more fun part. If you simply happen to edit and then save one build definition after the DST switch then it'll be saved with a different UTC time (due to the different UTC offset) and it'll run at the correct local time of day.