[TYPO3-english] PHP error in systext/lang/lang.php

[Sara Weale]

In custom draft workspace (enable frontend preview unticked) the 
following error occurs.

Fatal error: Cannot redeclare class language in 
.../typo3_src+dummy-4.3.7/typo3/sysext/lang/lang.php on line 88.

This worked in 4.3.3 but not in 4.3.5/7.

I have checked with the creators of nwt_workspace_preview and this 
extension works for their version of 4.3.7.

As no extensions have been changed between 4.3.3 and 4.3.7 I cannot see 
what else could be causing this error except the core Typo3 installation.

Any ideas/help would be most gratefully received.

Thanks,
Sara