If you are using Vista you can just go to your installation directory in the explorer and type 'cmd' into the adress bar. This will open a box with a command prompt at the current directory.
I don't actually remember if that works on 2000 or XP too, if not try:
Start -> Run -> cmd <enter>
Then use the following two commands to navigate to your installation directory:
cd <directory>
cd ..
I'll just give you a quick example:
As for an error message: usually just the first line is the information you need, like the MissingFieldException you have had before.