Can't copy/transfer .avi file to USB drive

[anonymous80]

OSX: Snow Leopard

Ok, so I have had this problems quite often.
I have a formatted (FAT32) USB drive and was copying/transferring several 700MB-1.5GB .avi files from the OSX desktop to the USB drive.
While most of the .avi files are flawlessly copied/transferred, I often realize one or two files among them were never copied/transferred.
No the original .avi files are not corrupted or bad.
(they are playing without any problems)
I tried everything (reboot, unplugged USB, etc), but cannot seem to find a right solution.
Is this a known bug in Snow Leopard OSX?
Any advice?
(Unfortunately I cannot update to OSX, because I have an early 2006 Macbook)

 

[GGJstudios]

While most of the .avi files are flawlessly copied/transferred, I often realize one or two files among them were never copied/transferred.

What size are the two files in question?

 

[anonymous80]

What size are the two files in question?

Smaller than 1.5GB
I don't think the file size is the cause because other files (similar or bigger size) were being copied/transferred.