If you happen to got one Microsoft Wireless Mouse 5000, either got it individually or from the Wireless Desktop 3000 (Like I did), you might found that the scrolling wheel doesn’t behave as usual that found in a normal mouse. It is noticeable having issue with Google Picasa (for zooming in and out), Adobe Photoshop, Open Office etc. where the scrolling wheel doesn’t do what is expected to do.
Having the hugely frustrated issue, I searched for the reason behind it. There is a user called niver has been explained his point of view about this issue:
Most (almost all) mouse drivers cause mouse wheel events with a "delta" of ±120. This is an arbitrary value that has been chosen by Microsoft in the past to allow finer control.
Since then, several programs use that value directly to test whether the mouse has been scrolled down or up (delta / 120 == 1 -> down, delta / 120 == -1 -> up, or something like that).
However, the Intellipoint software causes mouse wheel events with smaller "delta" value (the expected finer grain control), and programs which use the 120 value that way just fail to register the wheel movement, because in integral values, 30 / 120 = 0… [Source: Picasa support forum].