Win98SE and Comcast Hi Speed Internet (cable)?

OK, I finally got the Comcast Cable Internet connection set up and working,
by using the USB port. (I tried installing several a few PCI network cards
as suggested, and couldn't get any of them to work (even had a few blue
screens along the way, relating to some VFAT issues, and perhaps some IRQ
conflicts, but I'm very OK with just using the USB method to get hi speed
access, at least for now).

But - I have a slightly annoying residual problem here on my Win98SE
computer (and only on that one), which I haven't been able to resolve:

I have both Comcast Cable (for hi-speed) AND dial-up as a fallback (using
Earthlink, since my email account is with Earthlink, and is a POP3 email
account), without any major problems. (I have an account with Earthlink,
which is noth my email and Usenet provider).

However, whenever I'm connected using Comcast on the Win98SE computer, and
initially try to read email in OE (clicking Send and Receive), it always
*initiates* a dial-up connection, even though the USB Comcast cable
connection is connected and is working for IE, which is a bit annoying.

I've checked all my connection settings in OE and IE, and can't find
anything wrong in my settings. This problem doesn't happen with the XP
computer and Comcast, which has similar settings (although it uses an
Ethernet card, not USB).

Interestingly enough, after OE *initially* connects via dial-up and reads
the mail, OE promptly disconnects the dial-up connection afterwards, and
everything is fine from that point onward (meaning, if I click Send and
Receive again, it does not reconnect via dial-up, which is good!). But
when I close OE, and then reopen OE again, I have to go through this whole
thing again (always initially connects through the dial-up modem to read the
mail the first time).

Does anybody have a clue as to why it does this?