Hello Adam STONE,
Welcome to Microsoft Q&A forum. It's my pleasure to help you today.
I understand that it is very annoying when your mouse cursor keeps being stuck in the corner. Per what you've described, the cause of this might come from the trackpad itself, since it doesn't move when you remove the external mouse. In this case, could you please try to disable the trackpad and use only the external mouse to see if the issue persists?
- Go to Settings > Bluetooth & devices > Touchpad
- Switch it to "Off".
There is another way to try to fix it for now is to remove the touchpad driver from your PC and install it again. Please follow these steps:
- Type "Device Manager" in the search bar and press Enter.
- Find your Touchpad driver in the list.
- Right click and choose "Uninstall driver"
- Restart your computer and let the OS reinstall the driver on its own.
Please let me know if there are any updates.
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