There is no such limit in PHP.  All I can think of is that your browser limits 
the number of upload fields.  I tested this in Firefox and it worked fine both 
for 1000 text fields and 1000 file upload fields.

My test case looked like this:

<?php
print_r($some_file);
?>
<form action="ff.php" method="POST">
<input type=submit>
<input type="text" name="some_file[]" value="/Users/rasmus/foo.txt">
...999 more identical lines...
</form>

And my output was:
Array ( [0] => /Users/rasmus/foo.txt [1] => /Users/rasmus/foo.txt [2] => 
/Users/rasmus/foo.txt [3] => /Users/rasmus/foo.txt [4] => /Users/rasmus/foo.txt 
[5] => /Users/rasmus/foo.txt
...
[995] => /Users/rasmus/foo.txt [996] => /Users/rasmus/foo.txt [997] => 
/Users/rasmus/foo.txt [998] => /Users/rasmus/foo.txt [999] => 
/Users/rasmus/foo.txt 

Since there is no 128 field limit in the code and it works perfectly for me 
against PHP 5.3.2 running on Linux as in your report, I am pretty sure this is 
not a PHP issue.  Try another browser or look for other causes.