Thank you, GT500. And MousePad thanks, too.
I've solved this problem and I'm now using EAM 126.96.36.199 beta. Here's some information about what I did:
1. I had "Activate email scanning" disabled.
2. I changed the default settings in Office 2010 (File -> Options ->Trust Center -> Trust Center Settings -> Privacy Options), I disabled the following options:
Then the Office runs well, quite smoothly.
The Office I installed was simplified Chinese edition, it seems that EAM was analyzing the Internet traffic while Office starting by the default settings.
I restored to the default settings in Office, and added the Office components to the Application Rules of Guard in EAM as "Excluded"( which means I trust them), this problem was improved.
Disable all guards didn't work for this problem.
Hope these would be help. Feel free to inform me if you need more information.