I have Logitech easy call desktop set. (http://www.logitech.com/en-us/support/136)
I've recently changed my graphic card from nvidia to ati this usb set stopped working in ubuntu 12.04 after that..
I think it's not a hardware problem because i have dual-boot, and it works perfectly in Windows 7.
If I run
lsusb the devices seem to be connected. If I connect an extra mouse to any usb port it doesn't work.