http://www.answersthatwork.com/Task.../tasklist_i.htm
下面一點有

Iosdt
Iosdt.exe

(???)
You have a Trojan virus on your PC – IOSDT.EXE is its main file. You most probably tried to download illegal copies of Microsoft software, and got infected by this trojan virus as a result (it gives access to your PC from the Internet).

Recommendation :
Reboot your PC into Safe Mode and then do a search for all files and folders which start with IOSDT and delete them. Next, empty your Recycle Bin and reboot back into Normal Mode.