The biggest clue is the rows are all being returned on one line. This indicates line terminators are being ignored or are not present.
You can specify the line terminator for csv_reader. If you are on a mac the lines created will end with \rrather than the linux standard \n or better still the suspenders and belt approach of windows with \r\n.
pandas.read_csv(filename, sep='\t', lineterminator='\r')
You could also open all your data using the codecs package. This may increase robustness at the expense of document loading speed.
import codecs
doc = codecs.open('document','rU','UTF-16') #open for reading with "universal" type set
df = pandas.read_csv(doc, sep='\t')