[Owncloud] Problem after upgrade to 4.5.3

[Colin]

Hi folks,

I've been watching things for a while seeing all the improvements which 
have been great.

I have a cPanel server that uses a third party application installer 
called Installatron and one of the apps they bundle is ownCloud. They 
updated to 4.5.3 and the update has installed on the server in question.

Unfortunately the Windows sync client no longer works. It connects fine 
but when the sync runs it displays the red error "CSync failed to reach 
the host. Either the host or proxy settings are not valid".

This was with client 1.1.2 and persists after upgrading the client to 
1.1.3. This happens on existing folders and also new folders if I create 
them - even with nothing in.

My Apache logs look fine:

1.1.1.1 - - [30/Nov/2012:19:21:27 +0000] "PROPFIND 
/cloud/remote.php/webdav/FOLDER HTTP/1.1" 200 517 "-" "csyncoC/0.60.3 
neon/0.29.6"

If I attempt to access the webdav URL directly (after logging in) I get:

*Notice*: ob_end_clean() [ref.outcontrol 
<https://www.lanternhosting.co.uk/cloud/remote.php/webdav/ref.outcontrol>]: 
failed to delete buffer. No buffer to delete 
in*/path/to/owncloud/apps/files/appinfo/remote.php*on line*29*
Sabre_DAV_Exception_NotAuthenticatedNo basic authentication headers were 
found1.6.4

I found a post from earlier in the year about FastCGI which is enabled 
in Apache but there doesn't seem to be much resolution. The relevant 
.htaccess lines are there and mod_rewrite is supported. It was fine with 
4.5.2..

Any suggestions?

All the best,
Colin.