1) “X is not a valid Win32 application”

In the majority of cases you get this because your machine is infected or has been infected. The way to go is as follows:

Open up Windows Explorer and go to Tools>Folder Options and click on the View tab. Make sure Show hidden files and folders is enabled and Hide protected system files is unticked. Also, Hide extensions for known file types is unticked as well.

“OK” the changes.

NB: If, after you apply the changes, any of the above settings went back to what they used to be, ie Do not show hidden files and folders is selected, your PC/laptop is still infected.

Now go to C:\Windows\System32, find regedit.com and delete it. The file should look a bit greyed out because it has been set as a hidden file.

Now you should be able to launch regedit.

You have to apply the same approach if you get:

“cmd is not a valid Win32 application”

“ping is not a valid Win32 application”

“ipconfig is not a valid Win32 application”

“tracert is not a valid Win32 application”

etc.

Make sure you don’t delete the genuine file(s), though.

With regedit and cmd you can’t really go wrong.

The proper file is iconised and the bad one looks like the one on the screenshot above. In the regedit case, the bad one is located in System32, the proper one is in Windows.

With ping/ipconfig/tracert [the command-line applications], though, the icons, names and locations of the genuine and spoof files are the same so you have to distinguish them by extension (.exe for the proper files, .com for the bad ones) or based on the opacity – the spoof ones are greyed out.

2) ” ‘X’ is not recognized as an internal or external command”;

(click the screenshot to enlarge it)

In some cases, depending on the malware, you can get this error in addition to the error in 1).

Do the following:

Navigate to Control Panel>System>Advanced>Environment Variables. In the System Variables section, find the Path variable, click Edit and make sure you have the following:

%SystemRoot%\system32;%SystemRoot%;

Note the syntax – if you are adding it at the beginning, do it exactly as above. If you are putting it anywhere else, make sure they are separated by semi-colons:

;%SystemRoot%\system32;

;%SystemRoot%;

This should resolve the issue.