问题：Windows Mobile 6 sdk installation error, COM3 in use,please check the implementation
1. Windows->open "Run" ->click "regedit.exe" //点击windows按钮，在运行框中输入regedit，然后回车
2. Move to "HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/services"//找到注册表项HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/services
3. Delete "xpvcom" folder and restart Visual Studio 2005//删除xpvcom文件夹
4. In case if no "xpvcom" folder is found, try searching the same in other ControlSetxxx folders in place of CurrentControlSet and delete.//如果没找到，搜索以下
For me "xpvcom" folder existed in ControlSet001 and deleting the folder did the trick.
就是打开注册表，将xpvm删除。
然后重新安装mobile sdk