I had this very same issue and I was able to resolve it. In checking the Application Event logs, I noticed one Error: Event ID 33 (SideBySide). Contained in the Event ID was something along this (which included the path of the DLL file. Microsoft.VC80.CRT,processorArchitecture="x86",publicKeyToken="1fc8b3b9a1e18e3b",type="win32",version="8.0.50608.0"C:\Users\ADMINI~1\AppData\Local\Temp\{E1BCFFAB-7D90-4633-BDC3-3087F1E00F6D}\OMIL32.dllThe handle is invalid In searching a couple of other things based on this Event ID, you basically need to make sure that Microsoft Visual C++ 2005 Redistributable Package (either x86 or x64) is installed.  This would depend on what WAS installed at the time OpenManage 7.1 was installed. I did both for good measure and I no longer got an error message when uninstalling OpenManage 7.1!! it appears OpenManage 7.1 must have Microsoft Visual C++ 2005 Redistributable Package installed.  It also appears that these packages are NOT backwards compatible, hence the issues with uninstalling if you have a more current version (2008, 2010, etc.) installed.  I hope this helps others as I have been banging my head against the wall on this for days.
I have "inherited" a PE 2950 running 2008r2 core with hyper-v on which the DSM SA Data Manager service was stopping fairly regularly (at least once a week). I downloaded  OM 7.4 and attempted to update, but the 7.1 installed was the 32bit version. I got the uninstall string from HKLM\software\wow6432node\microsoft\windows\currentversion\uninstall when I ran the uninstall string it failed with failed to load library c:\users\ \appdata\local\temp\{GUID}\OMIL32.dll  if I now try to start DSM SA Data Manager or DSM Shared Services, I get a 14001 error that it cannot start because its side-by-side configuration is incorrect. I have tried installing the 7.2 32bit installer, but that fails with an OMIL32.dll library error as well.  Any suggestions on how to clean this up (that don't involve doing a fresh install of 2008r2) would be appreciated.
OM 7.1 32bit failed uninstall on 2008r2 core