Niko
I agree with Jon. Don't shut down at night. Don't hibernate. Don't do system standby. Don't shut down your hard drives. Don't turn off your monitors (OK, you may disagree here)
IF YOU HIBERNATE, you will lose connection to the database almost every time. You don't need to. Pick up a cheap voltage/amperage/wattage meter from Home Depot. Test with all modes. You will gain very little by shutting down at night. And, that will be more than made up for by a good night's sleep.
The jury is out on whether computers last longer staying on or off. I am a big believer of their staying on. When do you run antivirus scans? During the day? Most would run them at night. Backups? Usually at night. I have computers four to seven years old who need a Video card or PSU every once in awhile, but they are still going strong.
I would just have your screensaver set to automatically to lock the computer and have your staff log off. Shutting down the PC or logging off the PC or locking it will not affect your connectivity.
Also, just to be sure check your NIC cards and anything to do with being lazy turn it off. Like allow the computer to turn off power when not in use. You don't need that.
I can guarantee you that if you just log off the computers (not lock them -- which would still work), you will not have this issue.
