The microsoft website knowledge article 324516 gives 2 methods as a way of fixing this problem, but you might be very lucky if any of the 2 fixes the problem, alot of guys end up formating their systems and doing fresh windows installations or try wired ways of fixing it.
OK, the solution is very easy:
* right click your root windows installation drive i.e drive where you installed windows
* click properties at the bottom
* select security tab
* click Add and scroll down to SYSTEM account click add and click OK.
* allow Full control permission and click Apply and then Ok.
