Sophos for mac issues

Hi,

I've installed sophos free for mac but since I have several issues:

- I've tried to scan my drive, but it does not complete

- Since I've installed Sophos, preview crashes when viewing photos. It crashes on both of the users on the mac, while viewing jpegs or canon raw

My mac is using mountain lion updated, using the latest version of sophos. It's the latest version of the mini (late 2012) with an i7 and a owc fusion drive.

Thanks for your help,