The z3ta.dll file is created by rgc:audio software, and the file is a part of the z3ta+ Waveshaping Synthesizer module. This file would appear not to be intentionally malicious in nature, but it is still being reviewed. It can still create error messages in a computer and should be fixed by a registry cleaner if this occurs.
ZookaWare PC Cleaner is one of the more reliable companies offering registry scans and cleaning services, and they stand behind their work with a money back guarantee. In addition, ZookaWare PC Cleaner offers a free initial scan to potential clients who want to determine whether or not their registry is corrupted, and whether the cleaning services are even required.
There is no shame in having a computer that comes up with error messages — this can truly happen to almost anyone! Any time new programs are installed, or old programs are deleted, it is possible to corrupt or delete files that are necessary for the proper function of a computer. Happily, a registry scan can often fix the problem!