MY system had Win 7 Home Basic, after which I created separate partitions for a Linux Ubuntu installation. After doing this I had the option to choose between each OS at startup due to the dual boot.

Recently I've updated Win 7 Home Basic to Professional Edition. I have changed only the primary Windows partition and I haven't touched the Ubuntu partitions at all. Strangely, after doing the Windows upgrade, I lost access to Ubuntu. I am not prompted to login to Ubuntu during startup - I am being directly logged into Windows without being prompted.

Why is this so? Is there a way to recover the Ubuntu startup without reinstalling Ubuntu again?