How to get rid of my spoofing?

Hi, there!

I have a MacBook Pro 2.4 (Intel) running on Snow Leopard.

I've already had problems twice, with Yahoo and one with Hotmail accounts being spoofed from my computer. Although I've changed the passwords and used ClamXav, I'm still plagued by this and keep on spamming my Contacts with junk from my Mac.

These messages are being sent with a RE: as subject line, only and the text body contains the following links:

I want to give you an excellent possibility to solve your problems!... "http://complejopalmitos.com/com.page.php?ogoogleId=42ci4" which is: Canadian Neighbor Pharmacy

or this one...

Forget about hemorrhoids! . "http://rolet-drouffe.fr/sites.friend.php?xomaolid=55mj5" which is Canadian Health&Care Mall - Healthcare Online.

I've tried to Bing those pages and look for related malware, or whateverware I could find, but nothing comes up.

Also, most searches related to Mac's, instead of addressing the problem, they actually emphasize the fact that those issues do not happen in a Mac, which is quite irritating when you do have this problem, isn't it?!

I would appreciate any guidance on how to get rid of this.

Thanks!

spoofing

This is not from your computer, your passwords have been hacked and you need to go change them when this happens.

How can I be sure?

Thank you for the reply!

If this is not from my computer, which is the only one I use, so how come I had the incident 3 times and they were from 2 accounts we use only via our Macs, or iPhones? The account used twice was mine and the one used once was from my wife.

The first time I thought it was harvesting, but after the third time, within a short period of time, I started suspecting it is resident in the computer. How can I be sure it is not?

Because there is currently no malware in existence, in the wild, that will actually function in OS X in that way.

Change your passwords to a minimum of 9 semi-random characters using both small and caps and numbers and one of the following....
!<>@#$%^*-_+=|