There's a similar bug report link to bug report involving size of inserton CPAN, with a fix that I don't understand. Sybase isn't working out becuase it scrambles my files (see dbd:Sybase bit scramble). I'll update soon after trying a new driver.
Thanks again for the help, I've found it useful.
So in order to avoid spending money on a driver (although I did try the easysoft driver and it worked well), I wrote a c# script to update the column of my table which held the actual binary data from the files which I wanted to insert. So, although I now have to ftp the files to a windows box and then insert and delete them there, it works. There is a great example on how to do the c# udate on the web elsewhere.