Ok I probably know the reason.
If you have old PHP versions (4.x.x) you haven't 'file_put_contents' function and get PHP fatal error.
There is 2 ways to fix.
1. (better) Update PHP to 5.2.x on the server.
2. Create the file tp/data/settings/done_cache_rebuild2 (2!). No matter empty or not.
This issue DIDN'T affect on your trade, just on admin area.
UPDATED. I just released build #31 which compatible with PHP 4.x.x So if your admina area is blank, run tp/updater.php manually and make the update. Or make either p.1 or p.2 above.