System hangs up after waking up from sleep mode

Hi,
Welcome to Microsoft answers.

I suggest you to Check allow this device to wake the computer has a tick mark.

 Here are the steps:
1. Click Start, type Device manager in the search box.
2. Goto Device manager.
3. Click on keyboard, it will display your keyboard, right click and goto properties.
4. Select Power management.
5. Check Allow this device to wake the computer.
 
Follow the same procedure for mouse, restart the computer and check if it works properly.

I also suggest you to update your display drivers, you can logon to the manufacturers website and download the latest drivers and install.

For more information:

 http://support.microsoft.com/kb/266283

I suggest you to run the Power troubleshooter to adjust your computer's power settings, and check if it works properly.
 
Here are the steps:
 
1. Open the Power troubleshooter by clicking the Start button , and then clicking Control Panel.
2. In the search box, type troubleshooter, and then click Troubleshooting.
3. Under System and Security, click Improve power usage.
 
If you're prompted for an administrator password or confirmation, type the password or provide confirmation.
 
For more information, logon to:
http://windows.microsoft.com/en-US/windows7/Open-the-Power-troubleshooter
http://windows.microsoft.com/en-us/windows7/Sleep-and-hibernation-frequently-asked-questions
 
Let us know if you have any issues.
 
 
Thanks and Regards,
Azam - Microsoft Support.