[horde] Error Message

[horde@chosenofgod.com]

I am fairly new to Horde, recently I began receiving this message when I log
into Horde

Notice: Trying to get property of non-object in
/home/ruitera/public_html/horde/lib/Horde/IMAP/Tree.php on line 433

Notice: Trying to get property of non-object in
/home/ruitera/public_html/horde/lib/Horde/IMAP/Tree.php on line 435

Warning: Cannot modify header information - headers already sent by (output
started at /home/ruitera/public_html/horde/lib/Horde/IMAP/Tree.php:433) in
/home/ruitera/public_html/horde/templates/common-header.inc on line 4

Warning: Cannot modify header information - headers already sent by (output
started at /home/ruitera/public_html/horde/lib/Horde/IMAP/Tree.php:433) in
/home/ruitera/public_html/horde/templates/common-header.inc on line 5


I have not changed any settings that I know of. I believe my server host may
have upgraded to PHP5, from PHP4.4 if that could have caused it. Also the
really strange thing is that this error does not show up if I log in under the
account I most often use, however if I log in under ANY other account
(including my administrator account) this error message pops up in the left
hand pane immediately above the Sidebar panel. Any help would be greatly
appreciated!

-Alan