I really enjoy the trackpad two finger scrolling on my 2005 PowerBook. Until it goes wrong, that is.

Most annoying is the (default) behaviour of Firefox. Instead of responding to the two-finger horizontal scrolling by, say, horizontally scrolling, it moves back and forth in the history list. What ends up happening here is the you dare not use two finger vertical scrolling because, if you're not slavishly precise in your finger movements, you'll end up navigating back to some previous page. There's an easy fix to this though, courtesy of MacOSXHints:

In Firefox, type about:config into the address bar and hit return. This gives you a list of all possible configuration options. The ones we want are those that start with mousewheel.horizscroll.withnokey. Make the following changes by double-clicking the appropriate option in the list:

• mousewheel.horizscroll.withnokey.action => 0
• mousewheel.horizscroll.withnokey.sysnumlines => true

This successfully changes Firefox so that trackpad horizontal scrolling actually performs horizontal scrolling of the current page.

The other less frequent and somewhat less annoying problem is that the trackpad sometimes exhibits strange behaviour when waking from sleep. Most often, after a wakeup, one-finger trackpad movement (i.e. moving the cursor) seems to act as two finger movement (i.e. scrolling). This problem seems to go away after a few (say 15 to 20) seconds - but reappears on the next wake up from sleep

Apple has provided a help document that discusses this, which involves making sure you're using one finger (duh) or reseting the trackpad by "placing your entire palm directly on the whole trackpad for 3 to 4 seconds, then removing it in one smooth motion". I'm trying the latter to see if it makes a difference. One other interesting thing to note is that this problem (for me) only started showing up recently