Memory corruption under X86-64 environment

Hi all,

I have been playing around L4 on a x86-64 machine. I can run all of 3 
built-in toy programs (pingpong, l4test and grabmem) but I occasionally 
ran into memory corruption.

The bug can be reproduced fairly easily:

1) the page touch test (Test Memory-> Page Touch) fails to return.

2) The sub memu of Test Sigma0 is corrupted after a test on IPC (Test 
IPC -> Simple IPC)  is ran.

I'm new to L4, and I spent sometime investigating it but I didn't get 
any results.

Any suggestions are highly appreciated.

Thanks very much.

Cheers,
Haohui