What I've gathered so far is AOL was performing maintenance on part of its UPS system when a power surge/sag affected part of Loudoun County where AOL is located. Since AOL's peak usage is in the evening and late night, it is normal for them to perform maintenance during the "low-use" time period during the day. You are also more likely to get the "best" vendor support during the day. Parts of two computer rooms in one of AOL's data centers were knocked off-line for a minute or two. Several hundred individual servers needed to be rebooted. This affected parts of several AOL services such as Instant Messenger, e-mail, web searching. There were three different power anomolies in Northern Virginia yesterday. Normally an external event like a power failure, surge, or sag is handled by combinations of filters, upses, isolation transformers and generators. Its is relatively rare for an external event to cause problems in a top-level data center. I sent mail to AOL asking if I had the basic facts correct, but haven't heard back from them.