Try running this command in terminal before starting Steam and Half-Life 2: echo 0|sudo tee /proc/sys/kernel/yama/ptrace_scope This resolves the issue with Portal 2 on Ubuntu 12.04 LTS and maybe it will work for your problem. If this works please add a comment to relevant bug report: Many apps crash on Ubuntu 12.04 (ptrace broken again) (http://bugs.winehq.org/show_bug.cgi?id=30410)
