[CRASH] Windows 7 Restarts Without Loading?

I am running windows 7 ultimate 32 bit installed on a partition size of 270GB.The system worked for two months.Now when I start the pc, after the bios screen I get "Windows is loading files with a white completion bar.As soon as the bar gets completed or is full the system restarts.I tried start up repair from the install dvd using repair my computer.The message is failed to repair.Could not find os loader.Its a single boot system without third party boot loader.Tried restoring with an image backup.There is no difference.When memory diagnosis is selected from the repair options the pc restarts and the windows memmory diagnosis tool runs without any errors and on completion of the test windows boots normally.But if I restart or shutdown the pc the next time the system reboots after windows is loading files.I have interchanged the memory modules to and from another system to confirm the memory.The memory modules does not have any problem.