[UPDATE: It appeared that Wikipedia was back online as of about 4:30 p.m. ET.]
Wikipedia was offline Wednesday afternoon after an overheating problem at the online encyclopedia's European data center.
Wikipedia's technical blog said the site's servers shut themselves down to avoid damage from the heat.
Administrators tried to shift traffic to a cluster of servers in Florida, but "it turned out that this failover mechanism was now broken, causing the DNS resolution of Wikimedia sites to stop working globally," according to the blog.
"This problem was quickly resolved, but unfortunately it may take up to an hour before access is restored for everyone, due to caching effects," the blog said.
Trying to access wikipedia.com and wikipedia.org at about 2:45 p.m. ET produced a navigation error message.
One post to Wikipedia's technical blog, by a user named Jimmy, found some humor in the situation: "And so we remember Thursday, March 25, 2010 as the day every English speaking student failed their research papers."
Wikimedia Foundation.

From approximately 1:00 p.m. (18:00 UTC) to 4:00 p.m. (22:00 UTC) Eastern Standard Time (EST), the popular free encyclopedia Wikipedia, alongside its sister projects (including Wikinews), went offline due to major server outages. Downtime was later attributed to overheating at the Project's central data center in Amsterdam. 

According to a post made by Mark Bergsma at the Wikimedia Foundation's  technical blog, the servers "shut themselves down" to avoid further heat damage.

Administrators reportedly attempted a shift of traffic to the Project's servers in Florida. However, "it turned out that this failover mechanism was now broken, causing the DNS resolution of Wikimedia sites to stop working globally."

According to the Project's official Twitter account, programmers were able to resolve most of the server problems by around 4:00 p.m. EST. Since the situation with the servers in Amsterdam is still ongoing, some users may still experience lingering service glitches due to "caching effects".