forum goes blank after activating Xthreads

[deal4512]

My forum goes blank after activating the plugin
Forum link'

Full details:-
When i delete the cache folder contents xthreads.php and xthreads_evalcache.php. Then the forum opens. Now again when i refresh the plugins page in the forum the i get the error "The XThreads settings file (cache/xthreads.php) is missing or corrupted! If you have modified this file, please revert the changes and try again, or if you have a backup copy of this file, please upload it. Otherwise, it is possible to try to regenerate the file if the version installed is v1.64 - if this is the case, please click here to try to regenerate the file. " When i regenerate  the files (above two file in the cache) and the forum again goes blank.

I am trying with both new mybb 1.8 and old mybb 1.6 versions