I've used ZoneAlarm for a long time, and 2 months ago purchased the Pro version, along with the anti-virus suite (ZoneAlarm Extreme Security).

I've been playing a game (Team fortress 2) via steam (http://store.steampowered.com/) in windowed mode and happily browsed on the web or opened other apps while my game was open successfully for a long time (> 1 year) with the free ZA version and recently using my purchased ZA suite.

However about 2 to 3 weeks ago this all changed and now whenever I play in windowed mode and take focus away from the game it completely freezes my system, and requires a hardware reset.

I've altered settings for both steam.exe and hl2.exe to give them full access, I've tried game mode and nothing seems to help. The windowed mode works perfectly without zonealarm running. I've done the full reset of ZA to make it relearn etc, but no success.

I'm extremely frustrated as this was working fine until recently.

Any assistance is appreciated.