I don't know what has happened to my VS-2005. Whenever I double-click on the HTML table control in toolbox I cannot see the cell borders and table borders. what should I do ?

When you switch to the HTML view, is the Table present in code?  If so, can you make modifications to it such as changing the border width and then see if it's visible in the Designer view?

 Yes the table is present in HTML view and I can set all its properties in Design View as well as in HTML view but cannot see the table. Like I have changed the color of table borders from default to Olive but if I change it to default again then in design view I will not be able to see the table.

What happens when you put a GridView in the designer?

Also, do you have a separate CSS file?

 I am not using GridView control and I do not have any separate CSS file.

Try putting a border to the table and see if its visible in design view.also add some contents to the td so that you can check if its displayed in the design view.

What I asked was, as an experiment, is to place a GridView in your designer where your Table control?

Also, if you create a new project and then place a Table control on your web form, do you experience the same issue in a different project?

Just in design page press Ctrl+Q or go to View->Visible Borders 

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