I will use myself as a guinea pig so that hopefully any young savers, or aspiring near-early retirees can take stock, and consider.
Now, my personal situation is that I have a paid-for home, (value ~250K), several autos, including one brand new, all paid for (~90K total depreciated value), all of the furnishings, fixings, accouterments, play toys, big screen, brand new front loading wash/dry and other appliances, etc, that will last me 5 to 10 years into retirement.
The reason I bring all those 'incidentals' up, is not to brag or anything (especially in this august body of wealth!) but to establish that with my single, LBYM lifestyle, and the basics covered, and no looming major known expenses out there, I had calculated that having 750 -800K investment assets would allow me to give a green light to early retirement. I would rather have had a million, to give some safety factor but who wouldn't? Even if my balance dipped some, I would have been confident, but this crash took me to just over 500k -- down nearly 30% right off the bat! So when I read this thread real-time, I understood the compulsion to 'stop the bleeding' and to move to safety. Some in the thread told OP to wait a month (from Oct 2008) and then if the market slumped even more (it had!) to then move to money markets. Folks, had I followed that advice, then that would have locked in my losses almost exactly at the ebb tide, and destroyed my own chances to start/maintain early retirement safely.
Instead, I stayed the course. It was not fun. But I did it. And look at what had to happen to correct the loss, and put me right -- thank goodness, the markets recovered, but 30%, the size of the original slump, would not have done it!!!!
Newbies in particular: We need to be sure to always calculate our percentages correctly.
The correct formula is to look a the percentage change from what you started with, to what the result was. Many people do this basic operation wrong, and are not comparing apple to apples.
My balance is now up nearly 50% from the trough, yet I am just barely at my own 'go' threshold for pulling the ER plug.
Lesson: Losses hurt. A lot. The only thing that hurts worse, IMHO, is locking them in by trying to time the market at the worst possible time, in terms of outcome, and in terms of human behavior.
Stay the course.