Central Admin - Could Not Load File

Hi all, 

All of the sudden when trying to access Central Admin on my SP 2010 server, the page errors out and I get this:

Could not load file or assembly 'Microsoft.SharePoint.ApplicationPages.Administration, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c' or one of its dependencies. The system cannot find the file specified.

This server has been fairly static and no other updates or upgrades have been installed recently (last Windows updates on 6/12 and I was able to access Central Admin last week). 

Thanks!