Subscribe by email BUG

I got a bug in Subscribe by email.

When going into the Installed plugins section, I noticed that the Subscribe by email was listed twice. One was active and one inactive. The plug in was working just ok. But when I clicked on the "activate" link of the inactive, it created a fatal error and am unable to got back into the control panel. I opened a different browser and trying to just go to the home page is impossible. It displays the fatal error instead of the home page.

Here's the error:

Warning: require_once(admin.php) [function.require-once]: failed to open stream: No such file or directory in /home/................/wp-content/plugins/subscriptions.php on line 28

I removed the subscriptions.php file and was able to get the home page back and login to the admin control panel. However, now whenever I create a post, I get a blank screen and it doesn't take me back to the admin panel, only way is to go to domain.com/wp-admin again. ( i did copy back the subscriptions.php file but still get same result).