It happened to me a few times today. But when I click “Search” the second time it usually loads fine. Weird.
No, Google’s been working just fine for me today.
Given this is your second question with big sites giving you errors, I’d suggest scanning for malware.
If it was just not loading, I’d assume it was just your connection. But both sites returned errors. It’s likely coincidence, or possibly bit rot (i.e. something got messed up in memory and you needed to restart), but it doesn’t hurt to check. Sometimes these little errors are the only sign that something is going on secretly.
Internal server errors are generated by the server, not the browser. The other thread specifically mentions a 500 error.