|First, how many physical com ports do you have? The most a PC comes with now is 2. They don't necessarily have to be com1 and com2 but there's usually no reason for that to not be the case.|
If you have more than 2 physical ports then I take it you've added a serial card. If that's the case you need to make sure the com ports on the card use different addresses and, if possible, different IRQ's than the on-board ports. Com ports can share IRQ's but it's usually not a good idea.
If you've gone through 'add new hardware' and manually created a com port you need to delete them in device manager. You can't create a virtual port that way, as a virtual port creates its own and won't use a pre existing setting.
If you're unsure about the hardware ports you can just remove them all from device manager (but not the modem's, or any other virtual port). Then let 98 set them up again on next boot.