1. Note the devices that are sharing the IRQ with the USB host controller. Look in System Information > Hardware resources > IRQs.
2. Boot to BIOS setup (press Del, F1, or F10 at initial boot).
3. Go to the "Integrated Peripherals" section and disable one or both serial (Com) ports if you are not using them. Disable the LPT port if you use a USB printer.
4. Go to the "PnP/PCI" section and enable "PnP OS", "Auto" and "Reset Configuration Data". The last is a momentary switch and will be disabled each time you return here. It releases the BIOS lock on IRQs and lets Windows take over and is VERY important.
5. Boot DIRECTLY to Windows Safe Mode (continue booting and press F8 repeatedly to get the boot menu) and unplug any USB devices. Remove all USB software in Add/Remove Programs. Open Device Manager. Remove the USB root hub and host controller *in that order*. Remove all USB drivers. Look for duplicate or erroneous drivers and *remove them all*. Windows will reinstall genuine devices.
6. If you have any SB16 emulation drivers, disable them in the hardware profile (do not remove). These are DOS sound drivers and most don't need them.
7. Lastly, remove the drivers for the devices sharing the IRQ with the host controller. Windows should reinstall the drivers automatically.

At this point you have freed up 2 or 3 IRQs and reset Windows IRQ assignments. You can reboot and reinstall your devices *as per manufacturer's instructions*.

Bill