(after seeing weirdness in the message I sent, I will try it again so it looks better)
I checked against http://iss.astroviewer.net/. Today issue is better, however, still actual ISS posn about 100 miles ahead of SatPC32's displayed posn. My computer clock is off by no more than 1 second. For the clock to throw posn off by 100 miles, clock would need to be in error by about 15 seconds.
Just create an account at http://www.space-track.org/ and download the keps from there. I just logged into Space Track, and they have an ISS element set that was updated at approximately 2053 UTC today (not long before I sent this message).
Regardless of the freshness of the elements, it sometimes takes a little bit after the ISS has a boost raising its orbit to where the keps are back to being on the mark.
73!
Patrick WD9EWK/VA7EWK http://www.wd9ewk.net/