Copying Xcode.app to another location causes system lockup

Whenever I try to copy or compress Xcode.app on a computer (downloaded from the Mac App Store, currently version 6.1), the system completely locks up, just allowing me to restart with Ctrl+Cmd+Power.

It does not even matter where I try to copy it, to an external disk, to the internal disk, whatever.

Console.app does not show anything suspicious at the time of lockup.

However, when I try find /Applications/Xcode.app -type f -exec md5 {} \;, everything runs through and exits cleanly.

What the heck is going on ?

Is this some weird kind of copy protection from Apple ?

Do I have to fear some malware hiding ?

Anyone else having a similar issue ?

I have disabled any anti-virus software but the problem persists, even after I upgraded from Xcode 6.0 to 6.0.1 to 6.1, which curiously did not raise any problems.