This happened to me when I installed S60 SDK for 3rd edition beta. I am using Codewarrior v3.1 Personal. After installing S60 SDK for 3rd edition beta I was happy to see that even the *.h files were being included in the file list when using the 3rd ed SDK. However when I try using the S60 SDK 2nd ed FP2, a *.pref file is created in place of the MMP file with only the ff details

TARGET MyApp.app
TARGETTYPE app
UID 0x100039CE 0x10005B78

Not having an MMP file prevents me from re-importing the project. Removing all the SDKs and reinstalling S60 2nd ed FP2 and Codewarrior would solve the problem. Does this mean I will have problems working when both S60 2nd and 3rd ed beta is installed in my pc?