File Upload Error: Boundary length exceeds limit

[jose@iteso.mx]

 Greetings


Some users are reporting this message when they finish writing their email
with IMP 2.2.3 on Debian Potato with php 3.0.18 and apache 1.3.9.

Warning: File Upload Error: Boundary length exceeds limit. in
/usr/share/horde/imp/compose.php3 on line 90


 They are using:
Internet Explorer 5.
Version slide by slide mode
cipher strenght 128 bit


 This is the function which holds line 90 in /usr/share/horde/imp/compose.php3
 (I've included line numbers):

77 function gm_offset () {
78     $date = date('H');
79     $gmdate = gmdate('H');
80     /* Adjust for wrap-around, the difference can't be more than 12 hours.
81      * AFAIK, -1200 is invalid, the correct one is +1200 (ie: at New Zealand)
82      *
83      * CHANGED Oct 18 2000 (Submitted by <demian@coretech.co.nz>) to handle
84      * New Zealand daylight savings time.
85      */
86     if ($gmdate + 13 < $date) {
87                 $gmdate += 24; 
88     } else if ($date + 11 <= $gmdate) {
89                 $date += 24;           
90     }
91     $offset = $date - $gmdate;
92     if ($offset >= 0) {
93                 return sprintf("+%02d", $offset) . "00";
94     } else {                                            
95                 return sprintf("-%02d", -$offset) . "00";
96     }
97 }


  As a (probably irrelevant) side note, the server is located in GMT+6 
  (Guadalajara - CST6CDT at this time) and the users with the problem are on 
  GMT+8 (L.A. - Pacific Time)

  Any ideas?

 Thanks