This occurs with a Windows Installer package in Audit Mode. Testing in normal mode isn't really within the scope of how my software operates. It doesn't matter if it is done with 32 or 64bit OS. I have noticed it happening with multiple different installers, from notebook SCMs, Windows Live and Bluetooth software. The setup program will exit when "it is done" but it won't wait for the MSIEXEC it spawns to finish. So originally I had problems when my installer app would want to reboot the system before the install was actually finished. After adding in a "please wait" screen, it became obvious that MSIEXEC was taking a really long time to complete its task. So I went about debugging it. I ran a Procmon on it, and found that after the main installation was done, MSIEXEC would just kinda sit around and not do much of anything. Or if it was waiting on something, I can't see what it is doing by just monitoring MSIEXEC. The time is off in the log because the deployment test has a reset BIOS. Here is a timeline of events using Windows Live as an example. It logged over 1,000,000 events so I'm not posting the log file. If you want I can try putting it up on SkyDrive. @ 7:08:55 msiexec.exe creates its thread and begins the install @ 7:13:15 the install is (for all intents and purposes) finished, but msiexec does not exit. @ 7:13:23 Thread Exit @ 7:13:29 Thread Exit @ 7:13:56 Thread Exit @ 7:14:22 Thread Exit @ 7:15:02 Thread Exit @ 7:16:25 Thread Create @ 7:16:25 Thread Create @ 7:17:25 Thread Exit @ 7:17:32 Thread Exit @ 7:17:32 Thread Exit @ 7:18:53 Thread Create @ 7:20:00 Thread Exit @ 7:22:13 Thread Create @ 7:22:13 Thread Exit @ 7:23:15 Thread Create @ 7:23:15 Thread Create @ 7:23:15 RegCloseKey HKCR At the point of the RegCloseKey, the normal msiexec events show up and the process exits in less than 0.001 seconds. But you can see above there is a period of time, about 10 minutes of NOTHING being logged by MSIEXEC. So what is it doing during this time and what can be done to speed it up a little? Note: if the install is cancelled due to a reboot occurring at (say) the 7:13 mark, msiexec will rollback the installation! Attached is the msiexec.exe process info from ProcExp at about 7:15, during the "nothing doing" phase. Any ideas? msiexec.exe.txt