Is Age a problem

Hi Iam 48 yeaars old, I hold a hon degree in computers and post grad in business. I worked for the Defence Industry for nine years prior to leaving in 2003. Previously I worked in Oil simulation facilities and CAD/CAM. SInce leaving defence I have worked on sub-contracts as an analyst etc. My problem is getting my foot back into the market. I send out a number of cv’s each day but the replies tend to die after my initial chat. I have had interviews with large orgs, felt very good about them but still failed. I love IT and am always reading and working on technologies. I have my own network at home and just set up my own proxy server. Does anyone have any suggestions for a frustrated chap who just wants to do what I enjoy.