Sudo running as user=guest in parallels installer

I'm trying to install Parallels 8 under Mac OS X 10.6.8.

The issue: when installing parallels 8, or running the uninstaller from parallels 7, the install (or uninstall) freezes about 10% through. Checking Activity monitor, I see a process "lsregister" that's sitting there at 100% CPU. Let the computer sit for an hour, nothing changes.

Checking Console.log I see something weird:

8/31/12 6:46:14 AM sudo[6134] root : TTY=unknown ; PWD=/Volumes/Parallels Desktop 7/Uninstall.app/Contents/MacOS ; USER=Guest ; COMMAND=/bin/sh -c '/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/Launch Services.framework/Versions/A/Support/lsregister' -dump | grep -B3 'com.parallels.pkg.virtualization.hidhook' | sed -n "s,^.*path:.*\(/Users/Guest\),\1,gp;s,^.*path:.*\(/Applications\),\1,gp"

And indeed, the lsregister process that's showing up in Activity Monitor is listed as User=Guest.

This doesn't seem right : why would a sudo process be running as user "Guest"? That makes no sense, and is probably causing the hang.

Note: I did have the OS X "guest login" enabled, but I tried disabling that and it doesn't change anything.

I'm now totally hosed : multiple reboots, multiple attempts at running the installers (or uninstallers) for either Parallels 7 or 8 - always hanging with the lsregister running at 100%.

Any ideas about why sudo within a shell process would be running as Guest instead of Root?