It's because you installed Norton:
According to Microsoft technical support, these errors are linked to the following registry key:
This key has an VDD binary value that points to:
If the VDD binary value is removed, then the 16-bit subsystem returns to normal and is functional.
To solve this problem, you need to remove the VDD binary value first, and then update the Symevent files.
For more info: http://service1.symantec.com/SUPPORT...00030812224206