On my work PC, running Windows 7 x64, and behind my corporate firewall, I need to us a proxy to get out to the internet. I use a proxy PAC file, set in Control Panel >> Internet Options >> Connections >> LAN Settings.
When using SoapUI version 4.5.1 with no proxy settings configured (I am hitting a local service that does not require a proxy), it seems to wipe any configuration I have set up above (the proxy PAC).
I notice this when I begin browsing the web, only to find that I need to go in an reconfigure my proxy in Internet Options. I have reproduced this issue several times.