I had this exact problem yesterday and the day before. I had to contact namecheap to have them look into it. I had changed the name servers 2 days in advance and they still hadnt propogated. It ended up taking about 3 DAYS to propegate. Little dissapointing because usually it takes about 4 hours on every other domain host that I have used (ie. Godaddy). I hadnt had this problem before with namecheap, but I am seriously reconsidering.