[Hampshire] [OT] Forum help

A friend of mine runs a forum based on phpBB unfortunately she is not very IT
minded. Every now and again when a user goes to change their Avatar they are
unable to and it throws up a error message (see below). In this case in
question the user is in there user personal profile and is trying to browse
there PC to select the graphic file on there PC to be used as the avatar,
they select the file and the path appears in the box, they then click submit
at the bottom of the page then they get the error below.

Anybody any suggestions what the problem could be??

Tim

(The stars represent a word I was asked to remove by the forum owner, its a
long story its the same word in each case)

Warning: move_uploaded_file(./images/avatars/1930489481474af7c602664.gif)
[function.move-uploaded-file]: failed to open stream: Permission denied
in /home/******/public_html/includes/usercp_avatar.php on line 288

Warning: move_uploaded_file() [function.move-uploaded-file]: Unable to
move '/tmp/phpYk88zA' to './images/avatars/1930489481474af7c602664.gif'
in /home/******/public_html/includes/usercp_avatar.php on line 288

Warning: Cannot modify header information - headers already sent by (output
started at /home/******/public_html/includes/usercp_avatar.php:288)
in /home/******/public_html/includes/page_header.php on line 483

Warning: Cannot modify header information - headers already sent by (output
started at /home/*****/public_html/includes/usercp_avatar.php:288)
in /home/*******/public_html/includes/page_header.php on line 485

Warning: Cannot modify header information - headers already sent by (output
started at /home/******/public_html/includes/usercp_avatar.php:288)
in /home/*******/public_html/includes/page_header.php on line 486