To see if error is caused by webp.dll try to temporarily rename this file, or even move it outside of plugins directory in case XnViewMP loads everything he sees there.
dll installed on XP will be the same as installed on any other Windows. This way first copy of vccorlib120.dll it should find will be the one from Windows\system32. Then to see if it Vista version of vccorlib120.dll causes error, after installing redistributable on XP you can move msvcp120.dll, msvcr120.dll, vccorlib120.dll and vcomp120.dll from XnViewMP base folder to some place where xnviewmp.exe won't look for them. I had the previous standalone zip file of the HIEF dll files installed in the plugin directory prior to the latest upgrade.
It is a little slower than the previous XNViewMP version. It may as well happen that you already have this package installed, please check Add/Remove Programs in Control Panel. Perhaps it is a flawed dll in the latest version, or however win10 interacts with it and the auto-updated Microsoft HEIF plugins from the other day. Vccorlib120.dll seems to be part of Visual C++ Redistributable Package for Visual Studio 2013 which you can download from here. The malicious software can intentionally corrupt DLL files in order to substitute them with its own malicious files. They also have headers marking them as versions for Vista and up, but I think if they didn't want from kernel32.dll function they can not get, they could be used as fine as dll's for XP. Method 4: Scan your PC for malware to fix lpk.dll error Sometimes lpk.dll error can happen because of malware on your computer. These two are vccorlib120.dll from base folder and webp.dll from plugins directory. zip package with XnView MP 0.78 only two (if I didn't miss something) import function InitializeCriticalSectionEx() from kernel32.dll according to Dependency Walker.
I'm not Pierre (what a relief), but maybe you'd like to hear my opinion? Even if you don't, I'm going to post it anyway.