I use a product called Driver's Daily Log to keep track of my Hours of Service. Once a week or so, I print out my logs and send them in to the folks at HQ and everyone is happy. Rarely, they have lost a day or two (each is printed on a single page), but I can just print a fresh copy and send that in.
Last night my laptop crashed and I restarted it. I do a restart perhaps once a month or every other month, normally leaving it on in Hibernate mode while I'm bouncing down the road.
It turns out that it stores the data I input into one file for each month. So, December of 2007 has its own file, and January 2008 had one as well. Apparently, something went awry with the program or with Windows when it crashed and my current (January) file was blanked out.
Now I get to go back to New Years and recreate every stop, pickup, drop off, fueling, etc. for the past nine days. Thank goodness I'm taking time off.