The file d2htls32.dll is part of Doc-To-Help Hyperformance Tools by WexTech Systems, Inc. Doc-To-Help is a program that converts Word Documents into Windows help files. This dynamic link library is a piece of code that works with the WexTech version of the program to provide tools for the user.
However, Doc-To-Help was acquired by ComponentOne and is updated regularly. This particular file might be a legacy file left over from a previous version of Doc-To-Help, and may not be needed on the current version of the program. If you are running the latest edition of Doc-To-Help, you should clean your registry to make sure this dll file is not a ghost in the machine.
When programs are upgraded, sometimes references to older files can remain in the registry. Those references may eventually cause problems. You should regularly clean your registry with ZookaWare PC Cleaner to make sure your computer is running smoothly and error-free.