Until this morning my main PC (Windows 7 x64) has not exhibited any issues. I woke up this morning and logged on to find the "Bit Cryptor" virus running and all files on my PC and NAS(!) encrypted.
I've got some files backed up from my NAS to a USB drive and those on the USB drive do not appear to be encrypted however the backup is around 3 - 4 weeks old (not a major issue).
The "Bit Cryptor" program has a countdown clock (61hrs left at time of posting) and is requesting payment of 1 bitcoin.
Screenshot attached here: