usb devices not recognized

[webkat]

Hi everyone, I've a problem that sent me crying.

I'm a linux newbie, but i got a basic ubuntu system to run smoothly on my dell optiplex. specs:
ubuntu dapper drake 6.06
kernel 2.6.15-26

I plugged:
a wireless usb-dongle, got it to work with ndiswrapper
a usb hard drive, worked fine also
just when everything ran perfect, I changed the usb slots of the devices (put them fro the front to the back slots) restarted the computer and: no devices, no harddrive, no wireless.
I unplugged, plugged again before the restart/after the restart anything. The devices work on other computers, and other usb devices work on this computer.

Could anyone give me a hand in finding out what the heck the problem can be?? Again: both devices worked properly before I switched the usb slots, and they still work on other computers.

Thanks a million,

[Juan Pablo]

What's happen if you rrun the following command:

sudo lsusb

[webkat]

What's happen if you rrun the following command:

sudo lsusb

Thanks, that's the sort of command I was looking for to ckeck the usb ports.
here's what I get:
Bus 004 Device 007: ID 0840:009c Argosy Research, Inc.
Bus 004 Device 004: ID 0409:0059 NEC Corp. HighSpeed Hub
Bus 004 Device 002: ID 1260:ee22
Bus 004 Device 001: ID 0000:0000
Bus 001 Device 001: ID 0000:0000
Bus 003 Device 001: ID 0000:0000
Bus 002 Device 001: ID 0000:0000

so I guess usb recognizes the devices, but sudo fdisk -l does not recognize the harddrive, and "networking" can't find the wireless. I plugged a different usb hard drive just now, and it is recognized no problem. You've any suggestions?