Do you have the latest .net framework installed on your PC? I have used the scripting on a number of PCs, and never had this error.
With .net, it isn't nececarilly the latest version. Each version has a certain set of features. For example, if a program requires version 1, it won't work if you only have version 2 installed. You will still need to download version 1 and install that. At such a point, if you already had version 2 installed prior to installing version 1, now you have both versions installed. They don't overwrite each other, because later versions aren't actually upgrades of earlier versions, but rather are new feature sets (and they don't necessarily overlap at all).
So I will need to know the exact version of .net that Image Analyzer uses for the script feature, so that I can download that from Microsoft.
I just checked, and I do have the version of .net that it appears to be referencing in the error message. However, if you look more closely at the error messages, it says a file called "Files" is missing, and a file called "(x86)\MeeSoft\ImageAnalyzer\DotNetPlugins;C:\Windows\Microsoft.NET\Framework\v4.0.30319;C:\Windows\Microsoft.NET\Framework\v4.0.30319\WPF" is missing. These appear to be bugs in your program. It literally thinks that long semicolon-separated list of paths is supposed to be the name of a file, and it can't find a file with that name. Obviously no file is going to have such a name. Also, it's highly unlikely that there is actually supposed to be a file called "Files", yet it is also looking for that file (which doesn't exist).
And if you look more closely at the error message with the long path name it starts with "(x86)" which is the last 3rd of the folder name "Program Files (x86)". My guess, is that due to a bug in your program, it requires that Image Analyzer be installed in a path that contains no spaces, and when IA is installed in "Program Files (x86)" (where all 32bit programs go in a 64bit system) it glitches when it tries to read its own path, and that causes the rest of the code that follows the path-parsing code to malfunction, leading to it not being able to run scripts.
Note that I'm using beta version 1.38.3. I don't know if this bug has always been in IA, or if it got introduced by accident in one of the latest beta versions.