Page jump on load only in IE (caused by java sub menu nav)

Does anyone know why my pages with this java script naigation jump on load (only in IE after 2 seconds). I am just debating weather its neccesary to replace the naviation to solve this or if ther is a quicker fix.
Any info much appreciated

http://www.fishtec-coarse.co.uk/Index-Fishtec-Fly-Fishing.cfm

I'm viewing it under IE7, but I'm not sure if I'm seeing the jump effect.

When does the jump occur? What url? Do I need to click any navigation for it to occur?

Please provide further info.