I recently re-installed Windows Xp pro sp3 on my desktop (hp pavillion a700n). And once I restarted there is a white blinking dash and a black screen. So I re-installed over again and got same problem. I couldn't access safe mode with f8. So I figure I give windows vista a try but the same problem arises- cant access safe mode and trying the repair option when booting from the vista cd- doesn't find any problems. Before I re-installed the OS, the desktop was working. Can I fix these?