had trouble turning computer on

Wireless mouse and keyboard from Logiteck being used. In the morning found that neither would respond and computer would be in sleep mode. Changed batteries, re-synced, no success. Tried to shut down by holding power button to no avail, had to turn power strip off. Power restored, computer would reboot and all was well. Overnite, it would happen again. Second time around after repating above steps, this time computer would not boot up. After checking all connections and repeating to no avail. Tried switching red button in back of pc from 115 to 230 and back to original setting of 115 and pc booted up with no problem. What could have caused this to happen and what does that red switch do? What can / should I do next to diagnose and correct problem? Any suggestions?