White icons appear because the springboard icon cache is corrupting. You need an app which wipes the cache. There are three I know of which do this...
1) "Respring" - A free tweak from Cydia - Puts an icon on your springboard which resprings the device but ALSO clears the icon cache whilst you are at it.
2) iWipeCache - Does what you would expect an app called that to do...
3) Springtomize - A paid tweak which also clears the cache when you respring from inside the app or press the "Reload Settings" button.