Why is there such a big yetzer hara for fighting, stress and machlokes in families right before Shabbos? "Ein gibor k'misyaeish."
The biggest hero is the one with no hope left. Meaning: If someone's in a battle and they feel they have no hope for survival, they'll tap into hidden kochos to simply cause as much damage to the other side and go out with a bang. On Shabbos, the time for the yetzer hara for that week will be gone. "Kulan shvikin u'shvisin." When that is about to happen, the yetzer tries to create as much stress and machlokes about naarishkeit as possible in order to destroy whatever it can destroy before *it* is wiped out on Shabbos.
Similarly, this time before bias Hamoshiach, before "v'sa'avir memsheles zadon min ha'aretz," the sitra achra seems stronger than ever because it's on its way out when the yom shekulo Shabbos l'chayei olamim begins.
This is why the sitra achra makes tuma more accessible than ever before even b'chadrei chadarim of Jewish homes through computers, Blackberries, iPads, iPhones, and Droids. It's also why the koach of Yishmael seems to be taking over the world. Pretty soon the "memsheles zadon" will be removed from the world so they are trying take as much as they can with them by blowing up as much of the world as they can before being blown into nonexistace themselves.
It's a big chizuk to know that our big nisyonos are the expression of the last gasps of the sitra achra, rather than a sign that the other side is so strong. It's the final act of strength of the dying "gibor hamisyaeish."
May we merit to bring the yediah, the oneness of Hashem, and the ein ode milvado of Shabbos into the six days of the week and may we merit the speedy end to the nisyonos of this world and entry into the world of "v'chol ha'aretz deiah es Hashem" speedy-quick!