Programs Always Stop Working?

I just reinstalled my windows 7 (64-bit, home) because needed to kill some viruses. After reinstallation, most software will crash when double click, including media player etc. But If I run these software as administrator, it is OK.And double click IE 9 64-bit is good, no need to run as administrator, but IE 9 32-bit and Chrome will crash if they are not run as administrator.After the software crash, sometimes it will show some error message such as "the instruction at 0xxxxxxxxx referenced memory 0xxxxxxxxxxx. The memory could not be written."It is weird that I can not double click a mp3 to automatically open the media player to play the song, and constantly need to right click the player to run as administrator and drag the mp3 into player, too much trouble.I have done all updates of windows 7. It is still the same.