This problem is likely to be a lost connection. The connection between the MK300 keyboard or mouse and the USB receiver can be lost due to several reasons, including:

• Low batteries
• Moving the USB receiver from one USB port to another
• Moving the USB receiver to another computer
• Plugging the USB receiver into a USB hub or other unsupported device such as a KVM switch (your USB receiver must be plugged directly into your computer)
• Using your cordless keyboard and mouse on metal surfaces
• Radio frequency (RF) interference of more powerful wireless devices such as:
  • Wireless speakers
  • Computer power supplies
  • Monitors
  • Cellular telephones
  • Garage door openers

Eliminate any problem sources mentioned above that might be affecting your devices.

Before connecting your MK300 mouse:

1. Make sure you have fresh batteries in both your mouse and keyboard. For instructions on replacing the batteries, see Knowledge Base article 360023387753.

2. Turn on the mouse. For instructions on turning your mouse on and off, please see Knowledge Base article 360023387753.

3. Plug your MK300 receiver directly and securely into a working USB port on your computer.

4. Turn on your computer.

Follow the below procedures to reconnect your mouse and your keyboard:

Reconnecting your MK300 mouse:

1. Press and release the black CONNECT button on the top of the receiver.

2. Press the red CONNECT button on the bottom of the mouse.

3. Verify the mouse is working. If not, repeat the instructions above.

Connecting the keyboard:

1. Press and release the black CONNECT button on the top of the receiver.

2. Press the red CONNECT button on the bottom of the keyboard.

3. Verify the keyboard is working. If not, repeat the instructions above.

Additional Information:

If the above solutions do not resolve your problem, consult Knowledge Base article 12141 for instructions on contacting Logitech Technical Support.