What version of Classic Shell do you have installed? To see which version of Classic Shell you have without Explorer shell crashing, press Win+R keys together to bring up the Run dialog. In the Run dialog type this:
shell:ChangeRemoveProgramsFolder
You could try uninstalling Classic Shell and reinstalling again. If that doesn't work, try the Classic Shell Utility:
http://www.mediafire.com/download/3uker ... tility.exeand remove it completely.
Then try installing again and see if the Start Menu works without crashing the Explorer shell.
If the crash doesn't go away, you can try to capture a crash dump as per the instructions here:
viewtopic.php?f=12&t=6 and ZIP and upload the crash dump here.