Do you do the actual splitting manually (i.e. read line by line and dump into a new file) or do you use a utility.

If its the former, I suggest you take a look at some of the options available for splitting files. If you're on Windows take a look at this package, specifically the 'split.exe' utility.

Otherwise, I suggest you investigate further into exactly why your script is dying, as that's kind of important in fixing the problem.