There is only one file type that uses the .TRX_DLL extension:
Windows Startup File
File used by the Windows operating system that helps run .DLL files; loads files needed to run Microsoft Windows and other Windows programs; if a TRX_DLL file is corrupt or missing, Windows may produce an error or not startup successfully.
TRX_DLL files may appear as ONINTL.DLL.trx_dll or STINTL.DLL.trx_dll, which are produced when errors are encountered. This may result in decreased system response time or the computer freezing or crashing. TRX_DLL errors can result from viruses and malicious spyware.
ENVELOPR.DLL.trx_dll - Windows system file referenced when executing DLL files that identifies what libraries need to be loaded into memory.
Updated: March 22, 2013