I had a friend testing this on a Mac, and he did not experience any freeze.
You tested again with my latest sketch, right ?
Do you have any errors in "dmesg" about the ftdi driver ? I often have.
I'm using iMac G5 running with Mac OS Tiger, what is your friend Mac & OS ?
I believe so, tested the sketch you sent me by mail yesterday but to be sure, please send me again your last sketch.
We did test together via skype chat yesterday, no error message at all.
Not sure, I'll ask him. I remember he had to switch to Java 32 bit, cause he's on a 64-bit platform.
You can always get the latest version here: http://github.com/alvieboy/arduino-oscope