I had the same problem

Its because of one of your usb connections at the back. Remove them all and you wont find this problem. At some points you have to connect the other peripherals so go for a trial and error method by testing them one by one and finding the faulty one. Thats what i did. There was something wrong with the usb wire that came with my HP printer. I changed it and never used that port and its been working fine since.

The freezing part sounds like a psu problem