I'm having a problem with this too. I have my getsimple installation in a subdirectory, like so:
http://domain.com/subdirectory/
I have changed the website URL in the settings page to mirror the above (which is what it suggests), I don't have fancy urls enabled, or a custom permalink structure.
The url(/theme/...) function that gets called from various parts inside themes doesn't seem to take this into account, the result being that it doesn't find certain files.
E.g. I get:
http://localhost/theme/Flamingo2.2.2/assets/img/stripe.gif 404 (Not Found)
which is understandable as the file is actually at:
http://localhost/subdirectory/theme/Flamingo2.2.2/assets/img/stripe.gif
Any ideas?
(Also, while I'm here, I take it the search function on this forum is broken? E.g. if you search this topic for the words "timbowgs" and "citywide", which both show up in post no 2 in this thread, it should find this page, but instead returns no results. If the search function doesn't take multiple words, it's pretty much useless...)