File Not Found Exception

[Keith Thompson]

I am trying to run the arff.vector algorithm but am getting a File Not Found
Exception on my input directory.  I have checked and double-checked.  The
input path is definitely correct.  Someone suggested it could be a problem
that my Hadoop folder and my Mahout folder aren't in the same folder, but I
was able to run the Dirchlet clustering algorithm successfully specifying
both the --input and --output paths so I don't think that is the problem.
What other problems could cause this error to pop up?