Windows Vista is a version of windows that just modified and improved a liitle bit from Windows XP. What it changed is just added some newest security features and enhanced the GUI only. Windows Vista is inherited most of the bugs from windows XP. Since the Windows 98 available in market, Microsoft had been put alot of effort in taking out all the bug in the codes. One of the serious problem they face is that many of the old version windows programmers not longer working for Microsoft. Due to this, they left many unknown bugs in the codes. Microsoft tried to understand the coding but is too difficult to understand million lines of codes one by one. So, in my opinion, Windows Vista had so many vulnerability is because they not willing to rewrite the code in windows.