how can i fix my advent 9117?

The vndor being DSG (PC World/Currys) as Advent is a DSG Own Brand.

If the box is new take it back for a refund as you have given them an opportunity to fix it.

If not new then you need to reseat the memory cards. (Ensure that you have earthed yourself beforehand.) If that doesn't fix it, remove the memory cards in turn until the PC boots. The one that you have removed at that point will be the bad one.

T
March 2009