The first one is this:
SCRIPT1014: Invalid character stub.js?v=4f57d1d4ad7d, line 1 character 1
stub.js file looks like it has some wrong format:
Then the next one is this:
SCRIPT5009: 'StackExchange' is undefined
On other machines there's no problem with Internet Explorer 9 and Stack Overflow, I don't know what custom settings could make this out, I don't think I have some special addons installed. It only occurs on Stack Overflow.
What could this be?