Outlook Express on 2 computers- missing emails

Hi,
I noticed recently that I was missing some important emails as people would call me and ask what I thought of their response, and I'd say "I never got your response." So I looked in the norton spam folder, and I didn't have them there. I checked webmail and there were emails there that didn't show up in my outlook express.
Then I powered on another older computer that I keep for guests when they visit. I usually keep this PC off. The missing emails were in my CA antispam folder. So I uninstalled CA antispam on that computer. And I turned the PC off again.
Last night I missed 4 more emails that were not in my Outlook Express, but were in my webmail. So I powered on that computer in the guest room and the missing emails were in the inbox.
Why would this happen???? I then removed my account from Outlook Express on the guest computer. Will this fix the problem? If not what should I do- I feel like uninstalling Outlook Express from that computer altogether but it is not an option on Add/Remove Programs.
I don't want to keep missing important emails, so please help!

Go into OEs Message Rules and check there are no filters set.

Make sure OE is actually checking for emails (Tools/Options),

and that you don`t have any other anti spam software running.

Try the Firefox/Thunderbird email solution or Eudora,or one of

a number of other email progrmams, for trouble shooting or as

a permanent solution.