Cursor "sticks" when using laptop Synaptics trackpad following Windows 8 Pro upgrade

Question

I just upgraded my Windows 7 installation on a Lenovo Thinkpad W500 to Windows 8 Pro. Following the upgrade my cursor frequently does not respond to finger movements on the Synaptics trackpad. It either takes multiple attempts or a change of finger direction to get the cursor moving. The problem only happens when starting from rest; movements in progress are not impacted. Mouse and TrackPoint movements work fine. I've confirmed that it is not a sensitivity issue; the problem is consistent regardless of sensitivity settings and the firmness of my motion. Finally, following the problem I downloaded the most recent Synaptics drivers from the Lenovo site but the problem remains the same.

Update: I am able to reproduce the problem consistently as follows:

1. Move cursor to an arbitrary location
2. Pause momentarily, taking hand off the trackpad
3. If I try to move the cursor specifically in the down direction, it sticks. Other directions ok.

I installed Windows 7 side by side and the problem does not exist.

Solution

I eventually noticed that the cursor got stuck when I started my gesture from somewhere in roughly the upper 25% of the trackpad like so:

Synaptics Touchpads have a feature called "Edge swiping" that supports a series of gestures for moving your finger in a continuous motion starting off the trackpad and sliding on to it. Windows 8 apparently enables this automatically (at least it did in the case of my Windows 7 in-place upgrade). Given that the trackpad on my laptop is relatively small, the edge swipe region is a large portion of the trackpad area; in my case, it's roughly 1/4 of the vertical area of the device. Given that my initial finger placement much of the time occurred in this area, the trackpad would interpret this as an edge swipe gesture rather than a normal cursor navigation, so the cursor would appear to be stuck. I disabled edge swipe to resolve the problem.