[horde] pear?

[richard at norton-hall.co.uk]

I apologise if this is an often asked question. I can find no search facility 
on the archives.

When I log into Horde I get:
>>>>
Warning: logmessage(Log.php) [function.logmessage]: failed to create stream: 
No such file or directory in /srv/www/htdocs/horde/lib/Horde.php on line 187

Warning: logmessage() [function.logmessage]: Failed opening \'Log.php\' for 
inclusion (include_path=\'.:/usr/share/php\') 
in /srv/www/htdocs/horde/lib/Horde.php on line 187

Fatal error: Undefined class name \'log\' 
in /srv/www/htdocs/horde/lib/Horde.php on line 188

<<

I could find no Log.php file.
Looking on line I think it might be to do with PEAR I have downloaded the 
pear.horde tgz package and put it in the horde folder with no effect. I looked 
on the PEAR site but there are loads of packages I was not sure what I was 
looking for. Am I on the  right track and can any one point me in the right 
direction on this.

Regards Richard