My Logitech M705 started acting strange with scrolling. Ideally one scroll of the scroll wheel would produce the same amount of scrolling each time and in the proper direction. Instead it would jump around, bounce back in the wrong direction and be generally unpredictable. The fix that worked for me was updating the firmware on the unifying receiver.
The bonus is that the new firmware fixes a security flaw.
The instructions can be found here on Logitech’s site.
*Update* The site linked to above now has a login-wall. Reproduced below:
Instructions to update the Unifying firmware on Windows
Download and install Unifying Software:
To check the firmware version on your Unifying receiver, go to Unifying Software / Advanced, and then select the Unifying Receiver.
The version of the firmware is listed in the right pane.
– If the firmware version is in 012.xxx.000xx format, download and save RQR_012_005_00028.exe through the following link: http://logt.ly/0222
– If the firmware version is in 024.xxx.000xx format, download and save RQR_024_003_00027.exe through the following link: http://logt.ly/0224
Run the downloaded firmware package.
Open Unifying Software / Advanced, then select the Unifying Receiver.
In the right pane, click on Update Firmware and wait until the firmware update is complete.
Note: To have all the features working correctly after updating the firmware, please ensure that you have the latest version of SetPoint and/or Options software that supports your device.
Open the unifying software, go to Advanced, check which version you have, 012… or 024… and grab the corresponding file. Close the Unifying software, run the exe then open the unifying software again and go to Advanced. You should now have a firmware update available by clicking on the Update Firmware button.
It’s hard to tell if this fixes the problem just by resetting the receiver or it was the actual firmware that fixed it. Either way, the scrolling is now fixed.
Update: New firmware update tool released here.