Something seems very wrong, because disabling DEP is never a reasonable thing to do. People use VB6 all day long with DEP enabled and never have a problem.

This is because VB6 has a DEP exception, granted via a stock appcompat shim preinstalled with Windows:

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Globally disabling DEP is not a good idea. Once more it sounds like this Windows install has been trashed and reinstalling from scratch is the best bet.