While running an InstallShield based installer, my Windows 7 machine became unresponsive. After forcing a reboot, I can log in to the system, but explorer does not run. I can log in as a different user without issue and when I change UAC to its lowest setting, I can log in as the user that was performing the install. However, if I re-enable UAC, I am unable to get explorer to run again on login. I have checked the HKCU\Software\Microsoft\Windows\CurrentVersion\Run and RunOnce, but don't see anything that isn't configured to run on startup. I completed the installation of the software as the "good" user without issue.