Safe mode is a troubleshooting option for Windows that starts your computer with only basic services and functionality. If an existing problem does not reappear when you start Windows in safe mode, you can eliminate the default settings and basic device drivers as possible causes.
If you haven't installed any new programs or hardware recently, you can use the process of elimination to help you find the problem. Try starting all of the programs you commonly use, including the programs in your Startup folder, one by one to see if a program might be the cause of the problem.
The program might be incompatible with this version of Windows. Try using System Restore to restore your system to a point in time when it worked correctly. For more information, see What is System Restore?
The driver for the device might be incompatible with this version of Windows. For information about uninstalling a device driver, see Tips for fixing common driver problems.
If uninstalling or restoring the driver back to a previous version does not fix the problem, try uninstalling or removing the hardware, and then restarting your computer.
Try restarting your computer using Safe Mode with Networking, the only safe mode option that allows networking and Internet capabilities. If you can't connect using this option, be sure to rule out hardware issues by restarting your computer and also any network hardware you are using, such as a modem or router. For more information, see Troubleshoot Internet connection problems.
System Restore can return your system files to a previous point in time before you noticed a problem. For more information, see What is System Restore?
If System Restore does not fix the problem, try running Startup Repair from your Windows installation disc. For more information, see Startup Repair: frequently asked questions.