It wouldn't surprise me. .cfg/.config/.ini was once the 'standard' way of storing configuration settings*. I would expect that explorer.exe would contain some sort of legacy code that attempts to parse the file and, upon reaching a certain command inside the file, inadvertently continues to spawn new instanced of itself.
As Alan said; it would be most helpful to see exactly what text the .CFG file in question contains.
It's still possible to crash IE/Firefox/Opera/Safari & Chrome by attempting to open a HTML file with an infinite, self referencing loop. A program simply performs the steps it's told on whatever input you feed it. True; a program should validate it's input, but you can't expect a Microsoft dev to consider every possible way a user will attempt to torture the OS and prepare for it. Think of it like this: No matter how good your car's safety features are, you will probably die if you drive it off a cliff.
*I still prefer this method over the Windows Registry myself. It's more portable; human-readable and straightforward. All the software I write uses this "outdated" method, despite Microsoft calling it a cardinal sin.
I agree with you, I detest the registry, & the ini is much preferred.
I also agree that all possible ways cannot be tested, but it's 2012, & you'd think that they would have this fixed by now.
As well as having an easier way to reset all settings to default, because malware frequently changes explorer to their version, then leaves it unable to do anything when it is removed. Things such as this are a living pain in the neck, but there are a few tools that can fix exe problems, and other.
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But it should be inbuilt to ahem, restore default picture view, zip, explorer, jar, java, etc. User selects what to restore with checkmarks, & windows resets the defaults for the extensions.
Firefox has a reset feature & has had for a while... why not Windows?
* So far as driving the car off the cliff, yes, that will probably kill you, but that is something youd never (hopefully) consider doing on purpose.
Trying to set a file extension to always open with a certain program IS something you would consider. Especially if you had no idea what opens what.
In this case, I did it to see what would happen, & it quite surprised me that it isn't fixed in W7.
I suspect that many users try this with various loop results, as a result of system changes/malware/registry cleaning gone wild, etc.
Even as seat belts are one of a cars first lines of defense against flying out of a car, a computers first line of defense against changing extensions should be a simple reset button.
I see it all the time, where for example, programs have no options to NOT set the program that you are installing as default. So, user installs, it sets itself automatically as default, then user doesn't like said program & uninstalls or removes. There are broken extensions left that are now pointing to nowhere, & many reg cleaners, ahem, think these "unused" extensions are invalid.
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I think they should have the option to password protect the Windows folder & the file extension defaults, to prevent all programs from writing to the system area, or changing the default extension without your password.
In addition, there would be 2 registry hives. System hive, & user hive. Everyone knows that system areas of both the file system & registry are the most complex. If both of these areas were locked tight & all write access prevented, then only user areas could have write access.
If Windows needed to write, users would have a master Windows account that is password protected, wherein they are able to give ONLY Windows system operations permission to write to an area, while anything else is 100% blocked.
This would stop so much malware & viruses dead, that it isnt funny. Once malware is restricted & it no longer has the system folders to hide in, it will be harder for them to take over your computer, & virus scans will be very quick by eliminating having to scan areas that malware cannot penetrate.
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