re: Lagging issue with Bluetooth mouse on my desktop

Do you have anything else connected on the tower that could be causing interference? Also what kind of desk do you have? I've seen this happen when the tower is underneath the desk and the top is too thick and blocks the signal...and I've seen this happen with desks made of metal. Built-in bluetooth receivers tend to be weak and have a lot of issues...I recommend getting a mouse with USB dongle.

Also I know this sounds like a dumb question but have you checked the batteries in your mouse?