回复：我的机器看来问题真的太严重。

I remember once I installed MS's anti-virus software (trial version). When it expired I did not want to pay to buy the product. So I de-installed it. After de-installation I could not do any thing inclding opening the explorer. Since then I decide not to use any anti-virus software but prepare to wipe out and re-install OS/Appl.softwares any time. I believe it's the only way to completely clean up any virus. Note that no matter how good an anti-virus software is, it can only detects and fixes the one that it recognizes.