Several people have reported that error, and I've seen it myself. I've occasionally had success trying to open the file with a different method. For example, I usually open files by clicking on the file in Windows Explorer, but when I've gotten that error message I've sometimes had success with right-clicking on the file and choosing "Open" from the drop-down instead.
Does it open on other computers correctly? If so, the following probably wont work.
Make sure the file is local on your computer (not over a server). If you have more than one configuration, try opening it in a different configuration (in the SOLIDWORKS open dialogue).
If that works, go to Settings, Performance, Purge Cached Configuration Data, Save File.
Do this for each configuration.
Turn off Purge Cached Configuration Data again before trying to reopen.
Try opening it in another configuration or display state. Otherwise, you can open in the advanced configuration, creating a new configuration where everything is suppressed. Now you can unsuppress components individually until you find the offending item.
Unfortunately it may be that the file is corrupt but often they can be salvaged. If you can't do it then send it into your VAR!