Distorted mouse cursor, freezing computer (re-post)

I'm having a cavalcade of problems with my mouse, particularly related to the movement of the cursor about the screen. I have no idea whether this is the fault of Windows itself or something more specific, but I hope that enough people come through this forum to give me a working idea of who to ask.

The Problems

• The computer starts up with the mouse in a normal state, but will switch into the problem state some random time after being turned on -- the time can be a few minutes or a few hours. Restarting the computer sets it back to the normal state, but the problem state will re-emerge later.
• Some forms of the cursor, but not all of them, are distorted in both shape and colour. The distorted forms are stretched along the horizontal axis and have an "I'm trying to modern software in 256 colours" look. The "working in background", "busy", "resize" and "link select" cursors are the main culprits.
• The cursor sometimes gets "stuck" on an inappropriate form (e.g. showing a text cursor when there is no text there).
• While in the problem state, the computer occasionally freezes for a few seconds when the cursor is moved.
• Clicking does not always hit the exact point where the cursor appears to be. Sometimes, when navigating around a small button, the cursor jumps wildly around the button but never appears to touch it. The position in which I can select the small button is a position in which

What I've tried

• Running Windows 7, and the computer is fully up to date.
• The problems are not the fault of the mouse or its drivers. I have tried several computer mice and all of them lead to the same result.
• Changing the cursor style fixes the "256 colours" problem, but cursors remain distorted, and all other problems remain -- this is probably because the other cursor styles that come with Windows 7 are less colourful.

Other notes

• The problems started not long after I installed new GeForce drivers. I had not updated my graphics drivers for several years, and ran a great many updates at once when I was able to get the updater to work.
• At around the same time, I also obtained a new monitor for the computer.