Update 1:44PM EST
The site is back up and running and we do not foresee any further issues with this. Total downtime was a little less than one hour.
For those interested...
During routine system maintenance we noticed that the Event Viewer in our Windows server was recording an issue with an ISAPI filter. This filter was used in a previous version of our store and we felt it would be safe to remove simply to prevent any error from being thrown into the event viewer. We removed the filter and removed the file directory associated with it.
IIS, the web server software, was caching the file we removed. That means it would not notice we had removed it until the software was restarted, which it did today- a week later from when we removed the actual file. IIS crashed when it tried to load this file and it could not be found. The version of IIS that we use stops when previous versions would have simply noted the error and continued loading. The long and short of it is that an unused server component brought down the server. All is well as of now...
Thanks for bearing with us,
Shannon
Earlier: We are aware of an error on the server and are working to resolve it.