MDM.exe
(Microsoft)
Machine Debug Manager. Windows 98/ME. This is used purely by Technically Advanced Users and Developers, and in very specific cases at that. It is not needed in most normal day-to-day uses of a PC.
Recommendation :
There is a bug with MDM where it will regularly create zero-length temporary files in the Windows folder and not delete them. If you do not do regular housekeeping you can end up with hundreds of such files. Disable, or best, delete using Startup Manager. Note, MDM has a way of restarting of its own when Windows encounters certain conditions to prevent it from starting altogether many advanced users, ourselves included, resort to renaming MDM.EXE to MDM.EXE.OLD; that solves the problem permanently.