WEP is completely broken. Even if you do everything right, it's trivial for an attacker to access a WEP-protected network.
most of the time when a browser warns you that a certificate is bad there's nothing wrong
I've never had a false-positive browser warning. I assume you're complaining about Firefox's and Chrome's treatment of self-signed certificates, which is completely appropriate. Self-signed certificates should always be rejected, unless the user has manually added them to the keystore.