Sophos antivirus error

Hi.

With running: mac osx version 10.7.4, lion.

Sophos version 8.0.5

This message keeps coming up: 

Sophos anti-virus error

Shophos anti-virus is not running.

1. The error box (error box= sophos anti-virus error)Comes up on scanning, without connecting to the web.

2. The error box: Does not come up, connected to the web. Or then after.

3.  The error box comes up , when using the computer generally, but not connected to web at all.

4. The scanning bar: blue and white gets stuck... so have to stop and redo again.

5. The scanning bar: The blue bar starts from after 1cm to the right. Yet scans the same number of files that it always has done.

6. The scanning bar looks as if its going too fast , sometimes. So I restart. Then ok.

7. Sophos jams, so restart to solve.

The old Sophos version worked with lion.

Thanks.