pressing "Check Spelling" creates error

[Alderinks]

Binary package hint: squirrelmail

When using the Squirrelspell plugin in squirrelmail on Ubuntu-jaunty, if you press the "Check Spelling" button you get an error popup that states: ERROR: Error while writing to pipe.

Googled and found author message stating: "fwrite() has failed to write to a pipe created by proc_open()
Consult the PHP manual, your server logs, and Google to figure out why
proc_open() and family are not working on your machine. Possibly safe
mode, open basedir or SELinux restrictions?"

Not running SELinux.

Description: Ubuntu 9.04
Release: 9.04

squirrelmail:
  Installed: 2:1.4.15-4ubuntu0.2
  Candidate: 2:1.4.15-4ubuntu0.2
  Version table:
 *** 2:1.4.15-4ubuntu0.2 0
        500 http://us.archive.ubuntu.com jaunty-updates/universe Packages
        500 http://security.ubuntu.com jaunty-security/universe Packages
        100 /var/lib/dpkg/status
     2:1.4.15-4 0
        500 http://us.archive.ubuntu.com jaunty/universe Packages

php5:
  Installed: (none)
  Candidate: 5.2.6.dfsg.1-3ubuntu4.1
  Version table:
     5.2.6.dfsg.1-3ubuntu4.1 0
        500 http://us.archive.ubuntu.com jaunty-updates/main Packages
        500 http://security.ubuntu.com jaunty-security/main Packages
     5.2.6.dfsg.1-3ubuntu4 0
        500 http://us.archive.ubuntu.com jaunty/main Packages