By what you're describing with all the icons, it sounds like you do have Windows 8 (which I absolutely refuse to use on a PC).
One thing you might try before doing anything else (although I really doubt this will have any affect on your issue) is to run Internet Explorer in Compatibility Mode. Open Internet Explorer and up near the top, click on Tools-->Compatibility View Settings. (If you don't see this, right click up in the toolbar area and put a check next to "Menu Bar," then click on THAT Tools menu.) Click the checkmark for "Display all websites in Compatibility View." Then go to craigslist and see if it loads.
Next thing I would try is to download and install Google Chrome. Google Chrome is a web browser (like Internet Explorer). You use it just like you do Internet Explorer. You can download it here
https://www.google.com/intl/en/chro...gn=en&utm_source=en-ha-na-us-bk&utm_medium=ha
If the above two things don't work, You can try doing a system restore. Since I refuse to use Windows 8, I can't tell you step by step how to do a system restore on it. On previous Windows versions, System Restore is under All Programs-->Accessories-->System Tools-->System Restore. If you can find that, just follow the prompts and select a date prior to when you noticed the problem. Once it's complete and the computer reboots you should see a message that says something like "Your computer has been sucessfully restored." Try craigslist and see what happens.