Why?
A friend suggested conducting a system restore which enabled me to re-set the computer to an earlier date when it ran smoothly. We did the system restore together, on the phone, and to my great surprise, everything returned to normal. I ran a full system scan with Ad-Aware and was back in business on Saturday.
Thanks to everyone who wrote with solutions to the problem. Internet Explorer is surely susceptible to adware but I'm not ready to give it up just yet. Firefox is gaining ground though.