Somehow am being hacked - more than once.

Trying not to be TOO wordy - but difficult--
I've been "GOT" several times. Am dumfounded as "WHO and HOW"!
History: After several weird happening, and finally realizing it was a clown hacker, I bought Kaspersky Anti-Virus, Comodo Firewall, and after discovering that my wireless router was NOT secure, Bought a new LinkSys e-1200 and even did a full port check and got a perfect bill of health, saying "My computer was totally invisible". Felt safe and secure then. For a couple weeks all was quiet. Then the joker was back, turned off my tool bars,and a few other aggravting problems. Made repairs, then about 4-5 days later, this time he messed up my desktop -- blanking out the titles under the icons with what looked like (but know it could not be) a black sharpie. However, it was not a permanent damage,(Thank G.) when I rebooted it all went away.
His last attack almost jarred me out of my chair. ~(:-)) He programmed an audio file into my system, so my speaker suddenly sounded off so loud, with an sound of loud thunder, What the F? So realistic I actually went outside to check the sky. I then realized it was my speaker, cussed a bit, turned it down and went back to work, and hour later it hit again, realizing it was programed on a timer, turned my speaker off..
Since I added nothing but the best of security programs, (all items) then determined all of my ports were secure, and my computer was invisible, I am dumnfounded as how the heck the jerk or jerks still got in. Don't have anything else to check. Anyone having info or how this is possible --- would be interested in your opinion. Suspect it might be local, but my wireless router says the security is working. Weird!
Bill --- Ancient One!