workaround for 3GS on 5.1.1
on 3GS/ios 5.1.1 with NCS version 1.7.1 the 3G toggle is intentionally (I believe) removed from configuration. Adding it manually in com.jamied360.ncsettings.plist activates a warning message displayed when clicking an exclamation sign shown in preferences next to 3g toggle. Clicking the toggle gets Springboard into 70..100% cpu usage, which basically means it hangs.
Solved by replacing /var/mobile/Library/NCSettings/Toggles/3G/Toggle.dylib with the file from com.jamied360.ncsettings_1.6.2_iphoneos-arm.deb referenced earlier on this thread. many thanks to whom it posted.
I would not recommend doing this without some basic ssh/linux command line knowledge. If someone cares enough to translate this into tapping/clicking language, feel free.
Hope this is useful to someone else using a 3GS on 5.1.1 reading this thread.
Cheers.