Here I'll go over several issues I have found with the Arduino service & WIndows 7 (64 bit)
FTDI Driver strangeness & Jumpy Oscope
After updating my driver at some point (or unknowingly being updated by Windows) I noticed the Arduino Oscope behaving very strangly. When I selected a trace on the Arduino to display, the trace line would freeze, then flash quick, then pause, then flash - nothing like the smooth behavior it had previosly.