When the Quick Campaigns were first created we had a problem with members setting up frame breaking campaigns.  To address that problem we made it easy for people to report frame breaking.  When you join one of these campaigns you will notice if you look that the "Claim Credits" link changes after you claim your credits to "Report Frame Breaking"

Now here is the problem if someone joins your campaign and that campaign comes up again and they try to join, they are not joining your campaign, they are reporting it for frame breaking which stops your campaign.  When this happens you will notice when you view your campaigns it says "Stopped".  The credits will be returned to you.  Campaigns are only stopped for three reasons.  It expired, you personally stopped it or it was reported for frame breaking.

The only way to stop this is for members to realize that you may only join a campaign ONE time.  We do not think that people are intentionally stopping campaigns.  It's more a case of they don't realize that they have already joined it.  So we are asking all members to take a moment before you join that campaign and think.  If you already joined it don't try to join again.  You will not receive any credits for joining a second time, all you will do is report another member's campaign as a frame breaker and force that campaign to stop.