multiple duplicate newsletters being sent - help, how can i fix this?

[arielvered]

My newsletter to all forum membergroups containing a digest of all recent posts is usually sent every 8 days. Suddenly I (admin) have received it every day for the last 5 days.
I think members haven't been getting all these duplications, but on looking into it, i think they have been getting at least 2 duplicate emails each time it is sent out, and it doesn't seem to be sent out regularly.

Can anyone help me to sort this out?

[Illori]

are you using SMF 2.1?

[arielvered]

2.0.11

[arielvered]

Also, I've just seen that on the forum homepage, it says next newsletter due on 1 May. help!