i am getting an error when i switch from html to design mode in default.aspx page. the error is "Error Creating Control". if any one has a soution, please reply.

You need to look at the way you use qoutes in data binding expressions. Try replacing one set of double quotes with single quotes.

This is caused by a bug in the VS designer, but sometimes you can work-around it by changing some quotes.

since i forgot to place tagprefix for navigator control in default.aspx, i was getting this error. Later on, i was able to rectify the error. Any way, thanks englere for your prompt reply.