This has been discussed before. Conclusion:
It was wrong to fly the flag at half mast for the VA Tech students. It insulted our troops.
The only time to lower the flag is to pay tribute to someone who died while defending our country.
On Memorial Day, and at no other time, should the flag be lowered.
I wouldn’t go that far. Flying the flag at half-mast symbolizes national mourning, or mourning for some national tragedy. It’s not restricted to soldiers who die in the line of duty. Weren’t the flags supposed to fly at half-mast for forty days after President Reagan died? I think President Bush actually issued an executive order to have them flown full-mast at Independence Day, though the forty days were not up.