Are you using
Lazy Shell v3.0.1b?. This version should give you a warning before opening about trying to run the program in a 64-bit environment. I know, this error has been around since the very first release because Lunar Compress.dll is a 32-bit library file. Unfortunately since the source code for the .dll itself (the .exe code is, though, which is completely useless and redundant considering the real juice is in the actual library file) is not open-source then I wasn't able to incorporate it into the editor as a regular class.
If you compile a .Net app for x86 instead of "Any CPU", it executes in 32-bit mode on 64-bit OSes, and avoids this problem