Hi Ed,
Your proxy server is a router kind of thingy - up-line from your computer... Many cache pages for faster delivery of pages to their connect clients. If a "static" version is stuck (which is sounds like), it will expire and purge whenever it's programmed to - but can be a few hours, to a few days - and some have TTLs up to a week...
Make sense?
Best to ya'!!
JD