Have You Been Hacked?

I know I've had my Yahoo Mail and Facebook accounts hacked before. I figured that out when bad e-mail addresses suddenly starting bouncing back to my Yahoo Mail and posts I didn't make showed up on Facebook. 

I'm not sure what to make of this web site that tells you if you've been hacked. The hacks on my Yahoo and Facebook accounts don't show up. Entering my three main e-mail addresses using fredtyg at gmail, yahoo and sbcglobal, shows my gmail address was hacked once- something to do with the Forbes.com web site. I don't know if that's anything to worry about. My other addresses come up clean.

The explanation is here, but I'm not sure I understand it. Another one of those things that showed up on my Facebook page.