I ran it yesterday afternoon and it worked great. It created a file named
Saturday1201amUS_2009-12-21-15-46-00.21.log. This morning I did another test with my client and it failed miserably after creating a file named 'Saturday1201amUS_2009-12-22-'. A little investigation turned up that windows does not prepend a zero in front of the hours before noon so my executable file was getting a space in front of 9 oclock:
MyCommand.exe --output=Saturday1201amUS_Saturday1201amUS_2009-12-22- 9-47-20.31.log
It worked great after putting quotes around the file name.