I'm running;
Win 7 64-bit
Sandbox 64-bit with Sandbox 2 fix for Win 7

Once in a while, the frequency ranges from about 40 seconds to 5 minutes, while using sandbox all of a sudden my second most active window, on my desktop, becomes the most active window. After maybe 1/4 of a second Sandbox returns to being the active window.

Basically it feels like Sandbox is hitting Alt+Tab, wait 250ms, Alt+Tab, every 40 seconds to 5 minutes.

It seems to do it more often while in the Flowgraph editor, and it really breaks up my train of thought when I'm trying to get stuff done.

Has anyone else had this issue?

If your referring to the Sandbox fix I wrote, you need to right click the icon, go to options and untick "Auto scan for Sandbox". I only put the option there because someone requested it. Otherwise when you load Sandbox, just right click the icon and select "Force Manual Fix".