I've run into this when there is an extra CR/LF at the end of the file: In other words, your last actual line of data has a CR/LF and there is another CR/LF immediately following.

I've never had to do this, but I've read others have corrected the problem by setting the TextQualified property of the flat file connection manager to false or adding a text qualifier somewhere in the data. See here and here.

There's also a known bug when using fixed-width flat files although that applies to SSIS 2005.