I have a aluminum iMac, which has been working fine until now. A couple of hours ago I restarted it and went and did something else for a couple of hours. I then came back to find my keyboard and mouse not working, I double checked and they were both plugged in fine(I use the aluminum apple keyboard and a kensington mouse). I restarted my computer but it still did not fix the problem(I was still stuck at the login screen). I thought it might be the USB, so I plugged my iPod in, and it did not charge. While my iPod was still connected to my computer I restarted it again and as soon as the screen turned grey my iPod started charging and my mouse worked(the light turned on), but only until the grey apple logo appeared and it then stopped working again. I have tried every USB slot and none of them work. I'm pretty sure my computer was completely updated as well. Any help would be appreciated.