I had the same problem when I installed Ubuntu 10.10 on my HP dv7. I installed ubuntu on second partition and when I wanted to switch to win 7 it said that I have no win installed. The reazon is that pre-installed computers have hidden partition where is stored boot for windows. Ubuntu has a "instal in Windows" option which I didnt try, but I would like to fix this problem so that I could use backtrack 5 and win 7. I dont even have option: "instal it allongside windows" because of this partition. I think we have the same problem, if not, sorry for stealing your thread. So, any ideas guys?
sorry for my bad English