maybe the file is to big?
anyways, each file system has a set amount of directory, files, and maximum file size that it can support
if you are using a modern file system (reiserfs, xfs, jfs) then for most uses, you'll never get that "file to big" crap
if you are using older file systems (minix, fat/fat32, (ext2 is on the borderline, as modern computers are wanting more ***music, videos ...**** ), then you'll find the problem fat can only handle a file size of a few megabytes i think it was, minix/fat32 should be able to have around 64 mb files (or was that the max disk space?) ..
reiserfs and xfs can have huge file sizes, jfs (from stats a saw some time ago) has lower size limit, but its still high enough for most uses (certainly more then i have hard drive space)
so what fs are ya using? (and might want to switch a few years ago if you dare say fat/fat32/minix