When I try to highlight text, the cursor has a mind of its own 
It will highlight whole words, sometimes including punctuation marks, some times missing them. I will then have to move the mouse several times back and forth, hoping that it will eventually highlight the exact piece of text that I want.
How can I make the highlight start and stop exactly where the mouse pointer is?
We’re probably going to need some more information. Which operating system are you using? Does it happen in all applications (browser, text editor, word processor) or just some? Which applications are you using?
Windows XP. It is hapening everywhere, Word, IE, everything.
This feature is intended to help highlighting. When I slide the mouse with the left button depressed, it will highlight the whole word, before the pointer has reached to the end of that word. Its ok if you want to highlight whole words, but its a pain in the ass if you want just a part of the word.
I don’t know if this helps, but another option is to use the mouse to click to the begining of the word or phrase you want to highlight, hold down the shift key then use the arrow keys to highlight the portion you want. BTW this is how I deal with having a cruddy “pad” instead of a real mouse when I travel.
In Word, go to Tools > Options…
Click on the Edit tab.
You should see a checkbox that says something like “When selecting, automatically select entire word”
(This is in Word 2000, but I suspect it’s similar in later versions.)
I’m not sure about IE.