I eventually managed to narrow down what was causing all the grief and causing the build times to grow (previous post) and I thought I should update you all. The problem was the folders being created in the c:\Documents and Settings\<buildusername>\Local Settings\Application Data\Microsoft\WebsiteCache folder. After my last post I let my build run for 6 weeks and yet again the build times started to increase and I found I had nearly 60,000 sub-folders in this folder. When my build was taking 1 and 1/2 hours to run, this folder had over 406,000 sub-folders. A scheduled clear down of that folder is now in order.