USB problems after clean 14.04 install

Hello everybody!

I've just installed Ubuntu 14.04 on a brand new machine. Installation went smooth and everything seems to be up and ruing. Everything except the USB ports. I've got a wireless dongle for Mouse/Keyboard on one of the USB2 port. Both mouse and keyboard freeze at random times for no obvious reason. These freezes can take up to 30 seconds, but usually are over after 5-10 seconds. USB3 devices are not recognized at all. If I enter the BIOS and I plug in a USB3 devices I can see that it has been recognized. Not so on Ubuntu. No matter what device I put into one of the USB3 ports, it just doesn't show up.

Here are my specs: MSI 7693-040R 970 Gaming, AMD FX 8350, GTX 970 4G, 16 MB RAM, 500GB SSD. BIOS runs in UEFI mode.

Any help is highly appreciated!
Mats