Did you try my fix? I know it works, cause I did it. Do it and you too can schedule even when there is a pink box. Just type the date in the box. Don't use the drop down javascript thingamajig. Where you see the date just click it and type in a day. Also what about changing the time first then selecting a day? For sure I know typing the date in works. Not sure about doing the time first.
The interesting thing is time is that it's not a Thursday maintenance day so that doesn't seem to have any relation.