You wouldn't imagine that using computers could be dangerous, but there are a few situations that can result in accidents...
Trailing Cables
Computer equipment is often connected to lots of cables: power, network, etc.

If these cables are laying on the floor, they can cause people to trip over them

Solution: Place cables inside cable ducts, or under the carpet / flooring
Spilt Drinks
or Food
If any liquids are spilt on electrical equipment, such a s a computer, it can result in damage to the equipment, or an electric shock to the user.

Solution: Keep drinks and food away from computers
Power Sockets
Plugging too many power cables into a socket can result in the socket being overloaded, overheating, and a fire starting.

Solution: Never plug too many cables into a socket. Always make sure there are fire extinguishers nearby
Heavy Objects
Many items of computer equipment are very heavy: CRT monitors, laser printers, etc. Heavy items can cause serious injury if they fall on people.

Solution: Make sure equipment is placed on strong tables / shelves