Not all Yahoo emails are downloading into Outlook 2007

[B.A.K.]

I have a Yahoo mail account. I use Office 2007. I have set the setting to
leave emails on my POP server in Yahoo when mail is downloaded to Outlook.
Because I have that setting I have noticed that not all my emails are not
downloading to my Outlook inbox. They are not in my junk mail either. There
are from friends that are in my address book. It does not happen all the
time. For example I might get an email downloaded from my friend Beth in my
inbox in Outlook and then later in the day it won't download and I notice it
on my Yahoo inbox. Any thoughts? Do I need to go back to Yahoo for help? I
cannot totally rely on Outlook. I have to check my Yahoo inbox b/c some
messages do not download. Thanks.

 

[B.A.K.]

I also just put this under Outlook General. Didn't see that catagory when I
first posted.