One of the major causes of problems is the order in which they are installed. Read the manual and install either the hardware or the software first as instructed.
Try deleting that Yellow exclamation marked item in Device Manager, then disconnect all USB devices and reboot the computer. Now, connect the printer - Windows should see it immediately and load all the approriate drivers - you may need your installation CD for this. Once this has settled, connect all your other devices one by one.
PS if you've only got 2 devices, you should be able to connect each directly into the back of your computer - at least to makes sure they are working. Once they arew ok, then install the hub if your need to; if you then get problems, you know what's caused them.