I reinstalled 10.6.0 from the retail disk. It did not change the behavior, still scanned and quit.
I reinstalled 10.6.8 combo.
I grabbed a portion of the console system log from before and after the last attempt with 10.6.8.
It shows a bug. I did find a post regarding a security update bug with the location number, but nothing that relates to epson scan and that location.
I don't know if it really means anything.
Dec 3 12:45:46 Macintosh-2 com.apple.launchd.peruser.501[124] (com.hp.devicemonitor[213]): posix_spawn("/Library/Printers/hp/hpio/HP Device Monitor.app/Contents/MacOS/HP Device Monitor", ...): No such file or directory
Dec 3 12:45:46 Macintosh-2 com.apple.launchd.peruser.501[124] (com.hp.devicemonitor[213]): Exited with exit code: 1
Dec 3 12:45:46 Macintosh-2 com.apple.launchd.peruser.501[124] (com.hp.devicemonitor): Throttling respawn: Will start in 10 seconds
Dec 3 12:45:56 Macintosh-2 com.apple.launchd.peruser.501[124] (com.hp.devicemonitor[215]): posix_spawn("/Library/Printers/hp/hpio/HP Device Monitor.app/Contents/MacOS/HP Device Monitor", ...): No such file or directory
Dec 3 12:45:56 Macintosh-2 com.apple.launchd.peruser.501[124] (com.hp.devicemonitor[215]): Exited with exit code: 1
Dec 3 12:45:56 Macintosh-2 com.apple.launchd.peruser.501[124] (com.hp.devicemonitor): Throttling respawn: Will start in 10 seconds
Dec 3 12:45:59 Macintosh-2 pcscd[216]: Non-smartcard device launched pcscd [Vendor: 0X4B8, Product: 0X13A]
Dec 3 12:46:07: --- last message repeated 1 time ---
Dec 3 12:46:06 Macintosh-2 com.apple.launchd.peruser.501[124] (com.hp.devicemonitor[220]): posix_spawn("/Library/Printers/hp/hpio/HP Device Monitor.app/Contents/MacOS/HP Device Monitor", ...): No such file or directory
Dec 3 12:46:06 Macintosh-2 com.apple.launchd.peruser.501[124] (com.hp.devicemonitor[220]): Exited with exit code: 1
Dec 3 12:46:06 Macintosh-2 com.apple.launchd.peruser.501[124] (com.hp.devicemonitor): Throttling respawn: Will start in 10 seconds
Dec 3 12:46:07 Macintosh-2 /Applications/EPSON Scan.app/Contents/MacOS/EPSON Scan[218]: BUG in libdispatch: 10K549 - 458 - 0xe
Dec 3 12:46:07 Macintosh-2 /Applications/EPSON Scan.app/Contents/MacOS/EPSON Scan[218]: BUG in libdispatch: 10K549 - 463 - 0xe
Dec 3 12:46:07 Macintosh-2 /Applications/EPSON Scan.app/Contents/MacOS/EPSON Scan[218]: BUG in libdispatch: 10K549 - 468 - 0xe
Dec 3 12:46:16 Macintosh-2 com.apple.launchd.peruser.501[124] (com.hp.devicemonitor[222]): posix_spawn("/Library/Printers/hp/hpio/HP Device Monitor.app/Contents/MacOS/HP Device Monitor", ...): No such file or directory
Dec 3 12:46:16 Macintosh-2 com.apple.launchd.peruser.501[124] (com.hp.devicemonitor[222]): Exited with exit code: 1
Dec 3 12:46:16 Macintosh-2 com.apple.launchd.peruser.501[124] (com.hp.devicemonitor): Throttling respawn: Will start in 10 seconds
Dec 3 12:46:26 Macintosh-2 com.apple.launchd.peruser.501[124] (com.hp.devicemonitor[224]): posix_spawn("/Library/Printers/hp/hpio/HP Device Monitor.app/Contents/MacOS/HP Device Monitor", ...): No such file or directory
Dec 3 12:46:26 Macintosh-2 com.apple.launchd.peruser.501[124] (com.hp.devicemonitor[224]): Exited with exit code: 1
Dec 3 12:46:26 Macintosh-2 com.apple.launchd.peruser.501[124] (com.hp.devicemonitor): Throttling respawn: Will start in 10 seconds