FOLLOW THE STEPS BELOW. IT SHOULD WORK.
Deleting Temp Files
Here's How:
1. Click on Start, type the following command in the search box, and then hit the Enter key.
%temp%
This command will open the folder that Windows Vista has designated as the Temporary folder. These are folders and files that Windows needed at one time but are no longer useful. Everything in this folder is safe to delete.
2. To remove individual folders or files, hold down your Ctrl key while left-clicking on each item you want delete. Release the Ctrl key when you're finished.
3. To delete these items, hit your Delete key or click the Organize button on the toolbar menu, followed by the Delete option.
You will probably be prompted to confirm that you wish to Delete Multiple Items. Click on Yes to confirm.
4. If you'd instead like to remove everything inside the Temp folder, click on the Organize button and then choose Select All from the menu.
Note: If you're prompted that there are hidden files in this folder, just click on OK to bypass the message. A few hidden files hanging out in the Temp folder probably aren't important enough to worry about.
5. Again, to delete these items, hit your Delete key or click the Organize button on the toolbar menu, followed by the Delete option.
You will probably be prompted again to confirm that you wish to Delete Multiple Items. Click on Yes to confirm.
6. After all of the files have been deleted you can close the folder window and empty your Recycle Bin, permanently removing the files from your PC.
Tips:
1. You may receive a Error Deleting File or Folder message while the files are being deleted. This just means that one of the files is in use by a program right now. Click OK, close all open programs, and repeat the steps above.
Delete files using Disk Cleanup:-
1. Open Disk Cleanup by clicking the Start button , clicking All Programs, clicking Accessories, clicking System Tools, and then clicking Disk Cleanup.
2. In the Disk Cleanup Options dialog box, choose whether you want to clean up your own files only or all of the files on the computer. If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
3. If the Disk Cleanup: Drive Selection dialog box appears, select the hard disk drive that you want to clean up, and then click OK.
4. Click the Disk Cleanup tab, and then select the check boxes for the files you want to delete.
5. When you finish selecting the files you want to delete, click OK, and then click Delete files to confirm the operation. Disk Cleanup proceeds to remove all unnecessary files from your computer.
Deleting Prefetch Files :-
1. Click on the "Start" menu, and then select "Run", which will bring up a command box.
2. Type the word "Prefetch" into the text area, and click "OK" to confirm. The Folder C:\WINDOWS\Prefetch should now be open.
3. Press the keys "Ctrl", and "A " at the same time; by doing so this will highlight the entire contents of the Prefetch folder. Now that you have the entire contents of the folder selected, release the keys "Ctrl", and "A", and then right click the area within the folder. Select "Delete" to empty out the Prefetch folder. Please DO NOT DELETE the READYBOOT folder.
4. Click the "X" in the upper right hand corner of the "C:\WINDOWS\Prefetch" folder to close out the folder.