Boot Problem

Check for viruses in your computer. Click on the link below and do a scan on your computer, this is free:
http://www.trendsecure.com/portal/en-US/tools/security_tools/housecall

I am a trend micro engineer.

Here's a link that may prove useful to you. And another with specific instructions for running the repair. Before working with the registry, make sure to create a valid backup by running Erunt, available here.
I recommend you begin, however, by running chkdsk (see here and here) to check for corrupt files, then scanning for malware by following these protocols. Also do some system maintenance to improve the performance, at least the following steps. (See here.) And here's a great article that will help you to optimize the health and startup times of your system.
And finally, if you're working with an older system, it's probably time to update the drivers. Tutorial to guide you through that process here. If you're actually getting blue screens with stop error codes, let us know the exact error message and we'll help you to sort it out...
I hope this information allows you to resolve this issue. If you need further assistance, please post back with a comment to this thread.
If I've managed to answer your question or solve a problem, please take just a moment to rate this post....thanks!