Help - Unwanted Dial-Ups

Hi Folks,

I'm brand new to this bbs, so forgive if this is not the best forum to post this...

Got billed $30 on a phone bill for a weird call through an unknown provider. I called phone company, and they determined that the call was most likely our computer dialing (in the background) to some **** site (???!!?), probably as a result of an errant click on a pop-up.

Then it just happened again, this time a call to a 900 #, "Sports Info" line. An other $15.

Questions:
(1) Is there anyplace I can look for some kind of dial-up call log on my computer to confirm whether or not my computer actually made these calls?
(2) Is there some kind of settings I can configure to prevent this from happening again? Or do I need to get some kind of software that would help us prevent it?

Help, please....

TomG