hey steve,
there might be something in the current url which is telling the page to scroll to the bottom. i would try looking at the url:
1) cmd-opt-T to show the toolbar
2) make sure the url does not have some extraneous fragment (starts with '#') or argument (starts with '?')
3) if so, just press the 'Home' toolbar button. that should take you back home
i have seen gmail in particular add a fragment to the url that selects a particular mail message when the page loads. because fluid ssbs have 'session restore' on by default (look in General Preferences), this can end up being the url you load every time, and might cause this kind of behavior.
if that doesnt work this almost certainly will:
1) delete this file and folder:
~/Library/Preferences/com.fluidapp.FluidInsance.<your ssb name>
~/Library/Application Support/Fluid/SSB/<you ssb name>
2) recreate the SSB
td