[vpn-help] Network communication through VPN client causes Ubuntu to freeze

[Michael]

> However, if I try to connect to any hosts, my computer immediately freezes and requires a hard reboot.  
Hi!
I had exactly the same problems after upgrading from Ubuntu 10.10 to
11.04 (with Kernel 2.6.38-12-generic-pae).
After establishing the connection to a Bintec router with Shrew Soft
everything seems ok. But immediately after the first attempt, to connect
to a computer in the remote network my system freezes, not even "magic
SysRq" helped. Only solution was reset button.
I spent hours of investigating on web, compiling shrew soft in various
versions, changing firewall options and so on...

Looking at the loaded kernel modules showed me the solution:
I'm using a Intel Core i5-2500 CPU with Intel AES-NI for encryption and
decryption on the CPU for AES so the module "aesni_intel" was loaded.

After rmmod (and blacklisted) the aesni_intel module, i was able to
connect via shrew soft 2.1.5 from repository to the remote network
without freeze...

According to my research, "aesni_intel" e.g. improves  the performance
of "eCryptfs". I'm not 100% sure if other effects may occur by removing
the module but so far I've found nothing.

HTH,
Michael