things you can do:

--check your IE settings, tools/options/settings Is it set to Auto or loads every time

--check your Skin, is there code running in backgroud? does it do it on a dnn_blue skin?(is there custom caching?)

--check your modules  what modules are aroundn when its doing it? does it do it on blank page?(is there custom caching?)

--does it do it with Host?

--turn off your caching, what happens

--check the log, is the app restarting alot