Hi, thank you very much for your time and reply! I have tried yoor shorter script and added all the thumbnails but it has still the same effect. There would be maybe something wrong with the form processing itself, but I cannot understand why two are working (even if you select 1. and 5. file) and not more together. This is how it starts:

 
EOF

@ext = qw(jpg gif bmp);
$| = 1;
$match = 0; 
$encoding = 'multipart/form-data';
$q = new CGI; 
print "Content-type: text/html\n\n";
print $config{'header2'};
print "<div align=center><center><table border=0 cellpadding=0 cellspa
+cing=0 width=100% bordercolor=$config{'bordercolor'}>";
print "<tr><td width=100% bgcolor=$config{'colortablehead'} height=30>
+<b>&nbsp;Select your pictures to upload ( @ext )</b></td></tr></table
+></center></div><br>";
[download]

then there is the form and under that:

print "<hr width=80% size=1 color=$config{'bordercolor'}>";
print "<center><p><font face=arial size=2>Please click the \"Image Upl
+oad\" button only once,<br>Image Upload can take up to 10 seconds per
+ image uploaded.<br>Your images will appear below when finished.</fon
+t></center></p>";
print "<hr width=80% size=1 color=$config{'bordercolor'}>";
umask(000);  
mkdir("$config{'imageuploaddir'}", 0777) unless (-d "$config{'imageupl
+oaddir'}");

$file1 = $form{'upload_file1'};
$file2 = $form{'upload_file2'};
$file3 = $form{'upload_file3'};
$file4 = $form{'upload_file4'};
$file5 = $form{'upload_file5'};
$file6 = $form{'upload_file6'};
$file7 = $form{'upload_file7'};
$file8 = $form{'upload_file8'};
$file9 = $form{'upload_file9'};
$file10 = $form{'upload_file10'};
$file11 = $form{'upload_file11'};
$file12 = $form{'upload_file12'};

$uploadfile1 = $q->param('upload_file1');
$uploadfile2 = $q->param('upload_file2');
$uploadfile3 = $q->param('upload_file3');
$uploadfile4 = $q->param('upload_file4');
$uploadfile5 = $q->param('upload_file5');
$uploadfile6 = $q->param('upload_file6');
$uploadfile7 = $q->param('upload_file7');
$uploadfile8 = $q->param('upload_file8');
$uploadfile9 = $q->param('upload_file9');
$uploadfile10 = $q->param('upload_file10');
$uploadfile11 = $q->param('upload_file11');
$uploadfile12 = $q->param('upload_file12');

    if ($ENV{'CONTENT_LENGTH'} >= $config{'imagesize'} * 1024) {    
          print "<p><div align=center><font face=arial size=2 color=FF
+0000><p>Error - The image file size is too large\!</font></p>\n";
          print "<p><font face=arial size=2>Sorry but your upload imag
+e size can not be over $config{'imagesize'}kb.</font></p>\n";
          print "<p><font face=arial size=2>Please only upload images 
+with a file size less than $config{'imagesize'}kb.</font></p></div>";
          exit 0;
}

    if ($uploadfile1){
    $uploadfile1 =~ /\w:[\\[\w- ]*\\]*([\w- ]*.\w{1,3})$/g;
    $file1 = $1;
        foreach $ext (@ext){
                if (grep /$ext$/i,$uploadfile1){
                $match = 1;
                $type = $ext;                                
                }
                }
                if ($match){
        $newimage = ($config{'closedays2'} * 86400 + time);
        $file1 = "$newimage.$type";
        undef $bytesread;
        open(OUTFILE, ">$config{'imageuploaddir'}/$file1")||&error("Ca
+n not open $config{'imageuploaddir'}/$file1. $!");
        binmode OUTFILE;
        while ($bytesread=read($uploadfile1,$buffer,1024)) {
        print OUTFILE $buffer;
        } 
        close (OUTFILE);
                sleep 2;  # Wait 2 seconds
                }
                else {
                &error("<center><font face=arial size=2><b>Image forma
+t not supported.</b><p>$uploadfile1</p><b>Upload has failed.</b></fon
+t></center>");
                }     
                }
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And continues the same script for all 12 of them

I am seriously willing to pay somebody's time to help me solve this hell. Thank you