Problems with alienware Tactx Mouse

I bought my mouse recently (september 9th 2010) and didn't have an issue with it until a few days ago.  I remember the mouse have 5 dpi speeds that are changeable through the mouse buttons (under the left click), but now, I am only able to get 3.  Also, the mouse's "forward" and "backward" buttons on the side has it's functionality changed.  It no longer goes forward or backwards, it now resizes the window contents (exactly what happens when you do "ctrl" + mousescroll).

What's wrong with the mouse?  Is it defective?  Or did I somehow change the mouse's functionality without knowing?

I've tried other mouse's and they work fine.  I've also tried uninstalling and re-installing the mouse drivers and software, but the same thing happens.  I've also tried using the mouse on a different machine and the same thing happens.

Any help is greatly appreciated.

Thanks,

Chee.