参考：
http://blog.csdn.net/godcyx/article/details/7348431
问题原因：
That's a known issue where VS can't distinguish between SQL Client from VS 2005 (which needs NETCF V2) and from VS 2008 (which works with both V2 and 3.5). It should only happen if you have both versions of VS installed.
You can install correct SQL Client CAB manually and save emulator’s state, VS won’t deploy it again. On device you probably have NETCF V2 installed or in ROM so installation works fine.
解决办法：
I had your excact problem and in a way I have both VS 2008 and VS 2005 (this cause of Reporting Services 2005).
The solution to your problem is this:
Start your project (you'll get your error in the emulator, just click OK)
Look in the output of your build in VS 2008 and look for the line eg, "Deploying 'C:Program FilesMicrosoft.NETSDKCompactFrameworkv3.5windowsceNETCFv35.wm.armv4i.cab'
Open that local path and rightclick the cab-file. Check it's MB-size (in my case 2.58MB)
Share the folder to your network (the emulator should later connect to it)
Now when the emulator is up and running open it's File Explorer, Menu, Open path. Type \yourcomputername. Select the shared folder.
Copy the correct cab-file (for me the whole name wasn't visible so the size did the selection for me) to eg. MyDevice emp
Close your app in the emulator (if not done already)
Go to where you put the cab-file (temp) and click it. It will now reinstall CE Fremework and you will have to reboot the emulator.
When done make sure you Save the State of the emulator.
翻译后的解决办法：
问题原因：
".NET Compact Framework v2.0 could not be found."故障只有在同时安装VS2005和VS2008两个版本时才会报，如果只安装了一个或许是遇不到这个问题的。
解决办法：
在C:Program FilesMicrosoft.NETSDKCompactFrameworkv3.5WindowsCE目录下，如果是Wince设备则复制NETCFv35.wce.armv4.cab文件，wm设备则复制NETCFv35.wm.armv4i.cab文件，将文件复制到设备的“设备 emp”目录下双击安装即可。