Null extension is related to null system files. You can try to use registry repair to open null files.
NULL generally stands for the informations that can not be found by the software. If you get a warning like this "(null) file not found", probably windows can`t find a required file because of a problem on your computer. Actually it is a good thing for you, because if you get this warning there should be a virus that deleted.
Briefly: "virus is deleted, windows can`t find the virus"
If you want to get rid of this warning you may try registry repair software. Or, if you have Windows backup it is better to use it. To get detailed information, please take a look to following web pages below.
What to use null
Use Registry repair
which page related to null file
null Related Searches
You can check related links about null fileextension.