Does UE4 generate a crash report or is it just a crash report generated through Windows referncing the “DSMUserTask.exe” file?
If it does generate a crash report from UE4 can you upload your crash logs and dump files (found at [project]\Saved\Logs folder. Additionally, you can please send us the CrashReportClient.log file located in C:\Program Files\Unreal Engine\4.0\Engine\Programs\CrashReportClient\Saved\Logs.) as well as the string of numbers and letters that the crash reporter gives you when you submitt your report.
Did you submit the crash report if not, please do so and then give me the Crash Report String? It will link me to your submitted crash report in an internal database.
After some searching I cannot find any reason you should be getting this kind of error with the Launcher working and allowing you to go into 4.0.2 and not 4.1.1. I would recommend at this point, uninstalling the launcher and engine and re-downloading it from your account page. With the error related to a Windows Task Manager it may be that some registry file was corrupted at some point in which case uninstalling and re-installing may fix the error