Where, oh where, has my motivation gone?

I have hit a slump.  It happens every couple months.  What slump, exactly, have I hit?  The "I have no motivation to keep the house clean, but I am bugged by the dirty house" slump.  The problem is three-fold:
 1) Inevitably I get in a "media" funk and stop being as productive as I should be.  The little things go first, like making my bed every morning, and getting a load of laundry done every day.  Then the bigger things slip:  not unloading the dishwasher in the morning and letting the dishes pile up, letting the kids slide on doing their chores fully, ect.  Before you know it, the house that was neat and tidy becomes disorderly and chaotic. 

2) The children stop doing their chores.  This starts with me letting them slide on doing their chores fully.  If I am not doing my chores, out of laziness, who am I to enforce them doing theirs?  Then we enter the "I won't get my chores done and I'll just take the priviledge losses that go with that" phase.  You see, my kids are not allowed to use media or play with friends until all school and chores are completed.  That's all fine and good, except on the days that they simply don't care.  This causes a new problem.  I refuse to do their chores for them but I get bothered by the kids not doing their chores.   Then I NAG, AND NAG, AND NAG, because I want them to get their chores done.   

3) So, now we have a messy home that has gotten so out of control that mom gets overwhelmed at the prospect of getting everything back into order.  I enter shut down mode.  Shut down mode is where I am so overwhelmed by everything that has to be done that I do nothing at all.  I call it the "Mary Poppins issue."  I want to be able to just snap my fingers and have everything put itself back in order, but life doesn't work that way.  So, I do nothing, and the house gets worse and worse, and I get ANGRIER and ANGRIER until I snap. 

THEN the house gets cleaned with a vengeance, but no one is happy about the process because mom is a tyrant.  Life resumes as normal with everyone doing their work and mom checking chores to make sure they are done properly.  The house is tidy and runs well for a while.......until the next slump.  I KNOW that the solution to this whole issue is to just avoid the beginning steps in the first place.  It's a lot easier said than done.  So, if anyone has ideas to help "cure" my family of this reoccurring plague, please share your ideas!!!