Comment 23 for bug 1235918

After working around Bug #31589 (attachment 41923) Silverlight 4.x is able to individualize; however, Silverlight 5.x still has problems. It appears to create the individualization files and then delete them after it fails to connect to a named pipe:
0059:KERNEL32.CreateFileA(020ab990 "\\\\.\\pipe\\lrpc\\keysvc",c0000000,00000000,00000000,00000003,00000000,00000000) ret=7e87340e
0059:Ret KERNEL32.CreateFileA() retval=ffffffff ret=7e87340e

This named pipe business is not attempted with Silverlight 4.x, so creating this pipe would probably do the trick. A little googling finds this documentation:
http://www.hsc.fr/ressources/articles/win_net_srv/msrpc_cryptsvc.html