I am not sure really what is going on. I have an iCloud account as well as a gMail account in my Mail app. About 2 months ago, when I open it, for some reason all my calendar invites, both the ones I send to others as well as accept give me this issue -- sometimes it will go back for months and I will have hundreds of these windows pop up. I have verified all settings, deleted the mailboxes, deleted the accounts, rebuilt them, etc. Happens both on my desktop as well as my MBP. Any help or suggestions would be greatly appreciated. Thanks!
http://i67.tinypic.com/282gpir.png
http://i67.tinypic.com/282gpir.png