Looking at the files included within the downloadable DSMNetworkDiag package, it can be seen that the .dll files are very old, so removing them from the folder DSMNetworkDiag.exe has been downloaded to, will let DSMNetworkDiag.exe take the ones in the live installation, which are newer versions.
Concretely, the only files left in the folder after the suggested deletion operation should be now:
01/15/2009 03:39 PM 471,040 DSMNetworkDiag.exe
11/11/2008 05:59 PM 9,186 DSMNetworkDiag.xml
05/14/2009 09:04 PM 71,168 Readme for ITCM Network Diagnostic Tool.doc
03/25/2008 04:09 PM 550,560 WinPcap_4_0_2.exe
After removing the mentioned .dll files, the execution should ran OK.