What's wrong with Facebook?

Facebook went down today – and no, it wasn't just you.

For the second day running, the popular social network was inaccessible to millions of Americans, although Facebook reps said the outages on Wednesday and Thursday were unrelated, and caused by separate problems. As of late this afternoon – at least for this user – Facebook appeared to up and running, although some bloggers have reported continued hiccups with the search functionality.

According to reports from around the Web, the site first went down around 2:30 p.m. EST and continued drifting in and out of service through the day.

Users attempting to log in were greeted by an Internal Server Error message; the Facebook "Like" button, which is separate from the main Facebook site, also appears to have been affected. “We’re currently experiencing some site issues causing Facebook to be slow or unavailable for some users. We are working to resolve this issue as quickly as possible. This is unrelated to yesterday’s outage," Facebook reps told Mashable today.

CNN, meanwhile, has reported that the Facebook outage on Wednesday was caused by a third-party provider. That report was backed by information posted to the Facebook Developers Blog, which subsequently noted that the issue had been resolved.

The outages come at a time of incredible growth for Facebook. In July, Facebook CEO Mark Zuckerberg announced his site had hit the 500 million user mark. Meanwhile the analytics firm comScore recently announced that American users spent more time on Facebook – 41.1 million minutes – than they did on all Google sites, combined.

Have you had trouble signing on to Facebook today? Drop us a line in the comments section.