> 1) On my first page i am filling 3 comboes like Product Group, Product Type and Product On the selection of selecting Product Group combo my Product Type combo should be refreshed for the selected Product Group and on selecting Product Type my Product combo should be refreshed. But as i select the Product Group my whole page get (refrshed) i.e. whole page gets loaded again How should i avoid this ????

Dunno about this one, I imagine a client side script though.

>2) On my second page i am using the same 3 comboes on the nect page and i want the previous selected option should be carry forward on the next page and list index should be set accordingly for this i am using the method Server.redirect

Try redirecting to another site, but include the defauts for the combo boxes in teh URL, and in teh page, use Request.QueryString() to load the combos properly.