OK, not really a crisis, but...
One of the vagaries of the Muslim lunar calendar is that the declarations of a new month (when the crescent moon is visible) often differ in different areas. So Islamic holidays sometimes are declared to be on different days by different Islamic leaders.
This month is unusual, though, in that there are three separate declarations. This is important because the tenth of the current lunar month, Dhu al-Hijjah, is the beginning of the Eid al-Adha festival, which celebrates Abraham's "sacrifice" of his son.
This year, Eid al-Adha begins next Wednesday according to Saudi Arabia, Thursday in Lebanon and Friday in Iran.
By the way, the Koran never says explicitly that Abraham sacrificed Ishmael, only that he sacrificed his son. The entire chapter never mentions Ishmael's name. It implies that Isaac was born afterwards but it is not clear. For those interested in the topic, check out Sura 37:99-113 and especially compare translations.
One last piece of trivia: Chanukah, in Arabic, is Eid al-Anwar (The Festival of Lights.)