As reported elsewhere (multiple blogs and other locations), there has been a nasty little issue with Revit (all platforms) when exporting views, saving groups, etc., causing a fatal error and various error messages, due to a funky and bizarre "Y2K8" bug. The only workaround has been to reset your system clock to a date prior to 1/1/2008.
Autodesk has released new builds for all three Revit products to address this issue. This is one update you want to download and install:
Revit Architecture Y2K8 bug fix buildRevit MEP Y2K8 bug fix buildRevit Structure Y2K8 bug fix build