Sounds like your lib-common.php is corrupted (a topic that has been discussed here before and is also mentioned in the installation instructions).
Typically, it's one of the following:
- you used WinZIP to unpack the tarball
- you used Dreamweaver to edit lib-common.php
- (rarely
it became corrupted during the upload
Start with a fresh copy of lib-common.php (use WinRAR if you've used WinZIP before), edit the file in a text editor, not an HTML editor (use Notepad if you have nothing else) and upload the file again.
bye, Dirk