Hi Jay

I've testing this function and have found some odd behaviour. Keep in mind 
these files have in excess of 100000 lines.

If I compare the same file against itself, it works perfectly (both large files I'm 
testing on). If I compare short (30 line) files which only have a little overlap, 
again it works perfectly.

If I compare the two different large files I get very few matches (13 when I would 
expect 1000's).

Any ideas what would kill it? I'm conscious that one file is not english and might 
have some odd characters like the Spanish and French use.

At a loss now in debugging since it only bombs on really big files (it ends almost 
instantaniously).

Cheers

David