I can't view thumbnails on my clips,I have thumbnails on folders but no on files.?

Question

I don't know why I have this problem..everything was ok till yesterday..I have a strong antivirus and I am sure no any virus or...

Answer 1

To view files and folders as thumbnails
1.Open My Documents
2.Double-click the folder that contains the content you want to view.
3.On the View menu, click Thumbnails.
Note
•To open My Documents, click Start, and then click My Documents.
•In Thumbnails view, Windows displays up to four images from your folder on the folder icon by default. The images Windows displays are the last four images you modified.
•You can choose the picture that identifies a folder in Thumbnails view. The image file you choose does not have to be stored in the folder it identifies. For more information, click Related Topics.
•To remove the thumbnails view, on the View menu, click Filmstrip, Tiles, Icons, List or Details. Filmstrip view is available in the My Pictures folder, its subfolders, and folders based on the Pictures and Photo Album templates.
Source: http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/windows_fcab_thumbnail.mspx?mfr=true