As a Beta tester, I have installed numerous versions of FAS USB drivers, AE and firmware on Win7x64, XP32, XP64 and Win8x64. That's what we do as testers.
On PC's (win or mac) things don't just "work one day" and "not the next". If it was working yesterday and not today, there's a logical explanation. Could it be a FAS software bug? It's possible, but given the level of testing this software has had since Cliff's "clean sweep".. it's more likely that something changed. What changed? Idk, but it could as simple as a reboot - that perhaps loaded a USB 3.0 driver that took over the FAS driver priority?? idk. Do you have Win7 set to auto-update MS patches? That is the default setting BTW. I DO have the USB in a v2.0 port. USB 3.0 drivers are not OS generic and some work with FAS USB, some don't, and some work intermittently.
These issues - which Algrenadine stated appear to be mostly Mac related - need further research on the owner/user side prior to posting. There's a logical explanation for what is happening we don't know what it is.... What makes the troubleshooting tough is that you can't debug and fix something you can't duplicate.
I have EXACTLY the same [main] FAS setup as you stated you do..[ Win 7 64 bit, USB driver 168, AE 3.01, FW 11.03, Bot 1.2.5] and I don't have ANY connectivity issues at all. No-one releases software they they "know" has major issues.. like connectivity.