I have seen this problem arise anytime I update SC4 with the update provided at the SimCity.com. Not only does all the default parks appear blank but even other default lots lose the parks that are built together with the building. Only the building appears and everything else is blank. I tried finding the solution at Simtropolis but could not find any. I tried re-installing the game and updating again but it does not work. I even borrowed a copy of my friend and updated that but still the same problem arises. Even some custom lots are affected by this. For example, if I build a small park, it will appear as only a green patch. If I build a small plaza, then it will appear as only blank tiles. I know there is answer lying around somewhere but I could not find it even after extensive search at Simtropolis. Thanks in advance.