1. Mouse moved.
2. Wake on LAN, Modem, etc. enabled.
3. Virus, trojan, other pests.
A comment. Look at your post. Given this much detail only generic ideas can be offered. If it never worked then you ask the maker to fix it. If it broke today, system restore to yesterday. etc.
my computer keeps returning from sleep and never stays in sleep or stand by longer than 20 - 30 minutes