Okay, now try diz!!!
It is possible that your system's boot sector is infected and this was brought on due to viruses.
Start up the system in advance start up mode, See example below.
Boot into the system in safe mode, the computer shouldn't boot slowly in safe mode.
Select "run" from the start menu and type in "services.msc" (without quotes)
See image below
A dialogue box pops up showing you a long list of start up items.
See Image below
Now, check to see that non-windows services do not have the automatic start-up attribute. Also find other start up items that may have been put there by the virus, and disable the automatic start-up attribute as illustrated below.
Your Computer should boot in normally only once because you have not gotten the virus aut and it will discard your changes and go back, quickly run a virus scan with a strong antivirus scan - I recommend Bit Defender, Nod32 and/or [Kapersky Intenet Security 6
(thanks to Bigbrovar) 
]
This should solve your problem, if it dosnt; shoot me a mail -
nerve.it@gmail.com- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
I am aware that some people find it hard to boot into windows in safe mode, I will upload a simple utility that lets u select your desired start up method and reboots the computer. The tool is only 48KB, I will upload with my second post as only 4 attachments are allowed per post.
Good Luck!