Well, check if you have double clicked enabled. I don't know if you have the same touchpad manufacturer as I do, but my options are in:
My Computer > Control Panel > Mouse > Device Settings (Tab) > Settings (Button)
And I get a window like this:

I've underlined and circled what the important settings are. You can enable or disable double tap here (for the synaptics anyway), along with other neat things that can be exploited using the touchpad.
Here's a snip of what the explanation of this feature gives:
Quote:
| Tapping on the surface of the TouchPad is the same as clicking the left TouchPad "mouse" button. However, tapping is usually quicker and more convenient than using the mouse button. |
And, for Ace, I'd check your sensitivity settings. I find I get a similar effect to what you describe when I set mine very high.
And, if you don't happen to have a synaptics touchpad, it should still have the device settings under 'mouse' in the control panel. Or, if they don't have the settings under mouse, find out who makes your touchpad and look for their home site or some tutorials on your specific touchpad.
Synaptics came with some handydandy tutorials, so it's not a problem here. ^^