IPython not reloading file under Win2000

This is a bit bizarre.
It took me a couple looks to figure out what was happening.

I am using the 'run' command under IPython.
Error tracebacks print the correct line number of the
current file but *list* (and therefore highlight) that
line from an *earlier* version of the file.
This is particularly obvious when deleted lines
appear in the traceback printout.

After a bit of exploration, it seems that the lines
printed corrrespond to the file as first run. Changes
to the file are correctly run and traced, but the lines
printed appear to be from a cached (and obsolete)
version of the file.

Has anyone else seen this?
Any thoughts on how to fix it?

Alan Isaac

matplotlib list: I've moved this thread over to the ipython list.