Glad to hear it!
OK - let's deal with your points one at a time..... How did this happen?
- you possibly visited a compromised website without proper protection, or installed software that had malware embedded. I'm qulite surprised that neither MSE nor MBAM spotted the DNS problem, as it's widely known. Have you not used Google lately? - I believe that if it detects such a change it should display a prominent warning (but perhaps your particular DNS wasn't one of the ones it can detect) How do I prevent it?
- by ensuring that you keep windows up-to-date, and your anti-virus solutions also. Also, you need to be careful about where you go on the web, and what you download/install. There is no magic bullet. Was it only an IP setting on my machine that was changed?
- probably not - but if MBAM cannot find anything, it's likely that your AV managed to prevent or remove anything else. What about my router settings?
The main thing to change with your router is the access password - it's all too easy to get supervisor access to a router at default settings, if you can attach to it. Make sure that any NAT firewall in the router is turned on. Anti-Virus
- NEVER have more than one AV running full-time! They WILL conflict, and will often bring the computer to a complete halt. I agree that MSE and the Windows firewall is quite sufficient for the average user (it's all I use, and you should see some of the sites I get to!) - it also has the great advantage of being free
adding a weekly scan with MBAM free version is enough to keep the machine clean, most of the time - but nothing is perfect.