My PCs has 6 USB ports. All work but Device Manager onlyu shows 5. Any idea why?

WinXp. Abit AV8 3rd EYE, AMD Athlon 64 3500+, IGb ramMaybe all irq are used up! type msinfo32 in the run box.....click + hardware click + error devices.....No, that's not itmsinfo32  + hardware resources click the irq.......copy and paste the list......or type it.....IRQ 0      System TIMER      OK
IRQ 6      Standard floppy disk controller      OK
IRQ 8      System CMOS/real time clock      OK
IRQ 9      Microsoft ACPI-Compliant System      OK
IRQ 13      Numeric data processor      OK
IRQ 14      Primary IDE Channel      OK
IRQ 15      Secondary IDE Channel      OK
IRQ 16      NVIDIA GeForce FX 5500      OK
IRQ 21      VIA Rev 5 or later USB Universal Host Controller      OK
IRQ 21      VIA Rev 5 or later USB Universal Host Controller      OK
IRQ 21      VIA Rev 5 or later USB Universal Host Controller      OK
IRQ 21      VIA Rev 5 or later USB Universal Host Controller      OK
IRQ 21      VIA USB Enhanced Host Controller      OK
IRQ 22      VIA Networking Velocity-Family Giga-bit Ethernet Adapter      OK
IRQ 22      Realtek AC'97 Audio for VIA (R) Audio Controller      OK
IRQ 23      VIA OHCI Compliant IEEE 1394 Host Controller      OK
Device manager lists these USB

5 USB Root Hubs
5 VIA rev 5 or later USB Universal Host Controllers
and 1 VIA USB Enhanced Host ControllerIRQ 21 VIA Rev 5 or later USB Universal Host Controller OK
IRQ 21 VIA Rev 5 or later USB Universal Host Controller OK
IRQ 21 VIA Rev 5 or later USB Universal Host Controller OK
IRQ 21 VIA Rev 5 or later USB Universal Host Controller OK
IRQ 21 VIA USB Enhanced Host Controller OK

Windows WOULD allocated the six.......?If they were available.......a tweak but backup the reg first ok >IRQ's - Prioritizing

Start/Run/Regedit
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\PriorityControl. Create a new DWORD value called IRQ8PRiority and set the data to 1, reboot
I changed the registry as you suggested but DM still only shows 5What usb HUB is this. goto the makers faq website   it maybe a drivers/host controllers problem.....try update the usb drivers/ go to usbman and see the faq....unless it a BIOS upgade......check the  above first.....