This is often caused by other local radio interference in the same band. Do you or your immediate neighbours have a video sender device, these can cause problems. Is your cordless DECT phone base station close to the router or the PC?
Try moving these devices if you can and also try different channel numbers on your Router as moving the wireless transmissions to alternate channels can resolve these issues.
Hope this Helps
Ian Durrant MBCS
www.natdata.co.uk
Ian Durrant MBCS, January 2006