Why is my mouse randomly deselecting and unclicking?

This sounds like it could be a hardware issue. I posted some questions so you can help clarify your situation, but the reason this happens could be because (in order from most likely to least likely):

If you're on a laptop, input from both the external mouse and internal touchpad can interfere with each other. If there are mulitple pointing devices connected, it also can cause strange behavior. Windows wasn't designed to accept competing input from two mouse pointing devices at the same time and be able to deal with each separately. So if something is accidentally bumping the touchpad or something else while you're trying to do something with the mouse, it might cause things like you describe to occur.

Your mouse button is starting to go. Because of their constant use, it's likely that they'll be the first to go due to wear. The contacts might be a bit finnicky and have become sensitive to nearly indetectible changes in pressure on the button. Different behavior while using the mouse in different ways might cause misclicks. The behavior might be beyond whatever debouncing the circuitry in the mouse is able to do.

The battery could be losing its charge. If it's a rechargeable battery, it's good to note that they do tend deteriorate over time. It should take a while before it causes an issue, but it can happen somewhat quickly if you tend to overcharge the battery. Even if it reports being fully charged, it still may not be providing enough power to maintain reliable communication with the computer.

Your wireless signal might be getting interference. Perhaps another device could be interfering with the wireless communication between the receiver and the mouse. Even if the device doesn't transmit, they still can emit EM interference and cause other devices to behave erratically. But if you have something else in the vicinity that transmits on the same frequency and by chance is being picked up by the wireless receiver, it might be confusing the two devices, similar to trying to use two different remote controls to control the same TV at once.

Your USB receiver for the mouse might be malfunctioning. If it gets unplugged, stored, transported, and replugged-in quite a bit, it's possible that it experienced wear to the point that it began malfunctioning. Storage in excessive heat or cold can also cause damage to electronic components (same goes with the mouse itself).

The USB port you're using could be faulty. This isn't an unheard of situation. Perhaps the USB root hub isn't working correctly because it's misconfigured. Checking the Device Manager can help you determine if this is a problem or not. Or, there could be a physical problem with the port itself. Since they get a ton of use, especially with devices like this, wear can occur and there might be a broken solder connection, or bent pin, that isn't connecting reliably and interrupting USB communication with the device.

Or, you could be having conflicts with other USB devices on your machine. This doesn't tend to be the issue these days, as operating systems these days are very good at managing USB devices. However, there's always potential for a rare case to happen that causes issues. Again, the Device Manager can report if there are any resource conflicts.

To eliminate the fact that it's not a TOO NEW DRIVER issue:

• uninstall your updated driver, reboot, then install the driver that came with your mouse.

The driver that is sold with the mouse MUST work and is error checked. Newer versions can be become incompatible with older hardware, as new features are added gradually. I doubt they test it with ALL previous hardware - they test it with some, and they suppose it works with the rest.

To verify it is not a BUTTON HARDWARE issue:

• swap the mouse buttons in the driver (most software have an option for this, for left handed users).

The left mouse button is supposed to be less used, and if it works properly, it's a very high chance it's a button hardware issue. If it shows the same erratic movement, it's a different problem. In case:

• Microswitch is defective --> change it
• Solder joints got defective over time --> resolder it

See this post for instructions: http://www.kaibader.de/logitech-m705-how-to-fix-a-defective-mouse-button/

I have experienced this same problem as well and it is a nightmare. I'm a software architect/engineer so I work on computers all day.

Two things I have narrowed down that have both caused this are

1) Interferance from another device: I actually had one of those portable foot massagers under my desk. The type that has two rotational wheel with balls on them that massaged bottom of your feet. I determined that when I had that thing on somehow the electronic signal caused my mouse to act sporatic...it was crazy. So that was an easy one..I've also seen fans some times cause an issue.

2) It seems sometimes, especially when I've left my laptop idle for a longer period of time, days for example and it goes into hibernation that when I try to wake it up even after rebooting it seems to go on a LONG cycle of starting up, cleaning up etc. When it does this it seems get into this same state where it almost seems like the CPU is literally falling behind when trying to do anything. I've found after it eventually catches up the problem goes away.

Not saying this is your problem but these are definitely two I've found to occur.

Just experienced this symptom with a Logitech MX510 that I thought would outlive me. Changing to another mouse, problem gone. Trying the MX510 on another laptop, problem persists. So it's hardware. Will try to open and clean it.