This has been an ongoing issue with both my original and current ANRB and on several different computers. I leave my computer and ARNB on 24/7 and occasionally the ANRB will just stop working, the green power light is on but no activity is being shown. I pull the USB cable out and plug it back in to restore proper operation and it will work for a few more days before stopping again.
When I noticed it this morning I tried quitting the program and left the box plugged in, and it would not work again until I pulled out the USB plug and reinserted it.
My current computer is a current model iMac with 16MB RAM, Windows 7Pro-64 running within Parallels, but the same behavior has been noted on several other computers, including my prior Mac with the same setup as well as several other HP, Dell and Lenovo machines.
I have replaces the USB cable a couple times, used different ports on the machines and replaced the drivers and it continues. Some times I go a week or more, but usually about every second or third day I have to pull the plug...
Any other ideas?