Serious system issue - kernel extensions installed improperly I have just gotten an error message for every single kext file there is.
the error message goes something along the lines of:

The system extension "*file path*" was installed improperly and cannot be used. Please try reinstalling it, or contact the products vendor for an update.


If there is something I could do to fix it, let me know.
Try booting to "Safe Mode".  To do this:


Turn off your Mac.
Turn it back on and before you see the Apple logo on your screen, press and hold the Shift key until the Apple logo appears.
A progress bar should appear below the Apple logo - during this time your Mac is performing a directory check and loads only necessary Apple kernel extensions (among other small things).


After about 3 minutes or so you should load to either your login window or the Desktop, depending on whether you have automatic login enabled.  

If you no longer see the error messages, it's safe to assume the corrupt kernel extensions are third-party kexts.  Otherwise, if you continue to have error messages even when booting to Safe Mode, I would re-install OS X.

Good Luck!