Hi, my name is Chris and I'll be happy to help you today.
Ophcrack is pretty hit or miss. It either works or it doesn't. And if it doesn't, unfortunately it's getting tripped up on some of the hardware that's in your machine and there's not much you can do about it.
There are, however, some other similar programs that you can try that are also free. One that I've had pretty good luck with that's actually easier to use is PC Login Now.
You can find a complete step-by-step guiding to downloading and using PC Login Now by clicking the following link:http://pcsupport.about.com/od/toolsofthetrade/ss/pcloginnowsbs.htm
IMPORTANT: You MUST follow the guide step-by-step to be successful, so make sure to read through it very carefully.
If you're not successful with PC Login Now then you can find a list of other free password cracker programs at the following link:
If that doesn't resolve your issue, then I'm afraid that what you'll have to do is reinstall Windows either via the recovery discs that were supplied by the manufacturer or by using an original Windows installation disc. This will allow you to set the system back up from scratch and create a new account.
Good luck with it and if you have any other questions on this, just let me know. And if you found this helpful, please remember to click the ACCEPT button for me before you run.