Jeez, Dew, take it easy, it's only saturday morning.
All your usb devices combined need one irq, and they generally play nice together. Some of your other cards probably don't do well at sharing, and when you install the modem it or the card it's sharing with don't get along.
Check it out in settings, control panel, system- sometimes moving some cards around or disabling an unused serial port (or sb16 emulation, if you don't play dos games) lets things come together. Sometimes the mobo manual describes the interrupt sharing/setup scheme and can help you figure it out, move the cards to positions where the selfish ones don't have to share.... some bioses allow manual setting of irq's.
And yes, it is still possible to overload the irq sharing system, it's the biggest reason that the most recent boards and OSes use ACPI, where all the pci devices can use one interrupt. Installing an isa card in an acpi system is a ticket to disaster, however....
Hopefully, you'll get more suggestions.....
