Boss VF-1 Effect Processor

Hi,

I have encountered a problem that i don't know how to get out of.  I 
downloaded the "UpdSMF" upload from the net, as well as the new 
versions of the VF-1.  I followed the procedure of pressing the WRITE 
and LEFT Parameter button while turning on the VF-1, getting the 
message "Flash Update".  However, in the middle of copying the midi 
files from the computer to the VF, the screem shows message "Flash 
Chksum Err".  After finishing the progress of the upload, the unit 
stays the same, not prompting me to restart it.  I turned it off and 
tried several times, encontering the same problem every time.  Does 
anyone know where the problem could be from and/or what the solution 
is.  
Thank you.