Load your computer in Safe Mode (if you can not load properly) and begin:

1 Way. Windows 7 cleanup - Speed Up My PC
Disc clean up: Start - All Programs - Accessories - System Tools - Disk Cleanup, select С drive and ОК

Calculating...

select follow rows Downloaded Programs Files, Temporary Internet Files, Recycle Bin,
Temporary Files, then ОК and Delete

2 Way. Windows 7 cleanup - hard drive testing
Hard drive testing - this option will check the drive for errors:

• Close all files and programs.
• Click Start and Computer.
• In the Computer window, right-click С drive and click Properties.
• In the Properties window, click Tools.
• Then click Check Now and click Start.

If this process was failed, regenerate bad sectors.

3 Way. Windows 7 cleanup - Speed Up My PC
Remove $NtUninstall and .log files - click Start, in the Search programs and files box, type C:\Windows and press Enter. Find and delete all the files:$NtUninstall and .log

4 Way. Windows 7 cleanup - Remove Temp files
Remove Temp files - click Start, in the Search programs and files box, type %temp% and press Enter. Select and delete all the files.

5 Way. Windows 7 cleanup - Speed Up My PC
Remove unused components of Windows 7 - they further use of computer resources - click Start - Control Panel - Uninstall a program - Turn Windows features on or off, unselect all unused components of Windows 7

then click OK. Restart your computer.

Attention
You can also install components of Windows 7, but will need a disk with Windows 7.

6 Way. Windows 7 cleanup - Windows startup programs
Increase a speed of startup for Windows 7. Click Start, in the Search programs and files box, type msconfig and press Enter, then click Startup. Unselect all unused programs from the list,

then click Apply - OK . Restart computer.

7 Way. Windows 7 cleanup - Add Remove programs - Speed Up My PC
Remove all unused programs - more space, more reliable operation of the PC. Click Start - Control Panel - Uninstall a program, in the opened window select unused program, then above of the list of programs click Uninstall

and then follow the instructions to remove.

8 Way. Windows 7 cleanup - Disc defragmentation - Speed Up My PC
Increase a speed of Windows 7 - click Start - All Programs - Accessories - System Tools - Disk Defragmenter, in the opened window select something drive, with you want to defragment, then click Defragment disc. It starts the defragmentation process - it takes 0,2 - 2 hours.

Repeat for all the drives.

9 Way. Windows 7 cleanup - Speed Up My PC
Rebuilding damaged Windows 7 .Dll files - click Start - All Programs - Accessories, right-click Command Prompt and click Run as administrator.

Type on the keyboard: sfc /scannow and press Enter. You must see the following window:

10 Way. How to clean your registry - software registry cleaner
Registry cleaner - detail in the pictures, but if you are sure in yourself, you can clean up registries yourselves - way 11. If your computer works well again, you can do next - way 12, else you need System Restore.

11 Way. How to clean your registry - manually registry cleaner
Registry cleaner - remove the recording has been erased or improperly erased computer programs - Start, in the Search program and files box, type regedit, then press Enter. In the opened windows double-click inscriptions:
HKEY_LOCAL_MACHINE,
SOFTWARE,
right-click the name of the program (already erased), then click Delete - Yes .
Next click Start, in the Search program and files box, type regedit and press Enter. In the opened windows on the left double-click inscriptions:
HKEY_CURRENT_USER,
SOFTWARE,
right-click the name of the program (already erased), then click Delete - Yes.

12 Way. Windows 7 cleanup - Speed Up My PC
Remove all restore points - Deleting all but the most recent System Protection point. Click Start - All Programs - Accessories - System Tools - Disk Cleanup, select C drive and click ОК, calculating, in the opened window (the second picture of the way 1), click Clean up system files, select C drive and OK. Now on the top of the opened window click More Options, then click the second button Clean up from the top, then click Delete - OK - Delete Files.