In the calender grid of a month (displaying 3 months) the week numbers aren't correct :

Example :
Okt 2012
Wk 43 - 22 okt > 28 okt
Wk 44 - 29 okt > 04 nov
Wk 45 - 29 okt > 04 nov
wk 46 - 05 nov > 11 nov

There is a double week ? (44 - 45)

I planned alot of time slots and it looked like it works. Now 3 days later i check it again and all my slots in Oktober and November this year aren't available anymore ? How can that be ?