Live Mail “message cannot be foud”

Im using Windows Live Mail on Windows 10. Pop account I think. After a day or two of being in my inbox, my emails give me a "Message can't be found" message. I cannot delete emails if there are more than one in a cluster and have to delete each one singularly. Then the next day when I turn on my computer these deleted mails return and I have to delete them all over again. Im really getting tired of this