QUOTE(riven3d @ Jan 2 2006, 01:38 PM)
remove the expansion packs if you can
Unless there's something from one, or both, of those that you want to keep for use. One thing though, you SHOULD be able to scroll using the slider on the scroll bar. This has worked for some, but not everyone.
What I've done is uninstall the entire game. I then zipped all the remaining objects I had and am still in the process of determining what objects I want to keep. It's been very time consuming to do this, but it may well be worth the effort in the long run.
After reinstalling the game, I renamed the object files. I added 'rct-', 'ww-' or 'tt-' to the beginning of the filenames. Hasn't caused me any problems so far as the game doesn't use the filename to find the objects.