Are you sure this isn't an intentional effort by Yahoo to reduce server traffic? When I limit the number of stocks updated there's no issue. It's only when I update a larger number that is issue arises.

They have other ways to reduce server traffic without sending bad data.

So? Who's to say this isn't another way they're employing?

That's pure conjecture. Sending bad data intentionally would only serve to harm their reputation.

The one thing I do know is that I have not yet received any response to my report of this problem.

Correction, apparently I did receive a reply on Saturday in my Yahoo inbox, which is an account I don't use often. They said: "Our engineering team is currently working to correct this, and our goal is to resolve the issue as quickly as possible." It's basically a form-letter reply, but at least they know about it.

Thank you for informing us Anatoly.

on 7/22 I followed the instructions above about downloading/extracting a new PSMQUOTE.DLL, saving the old one, and replacing it with the new one while PSM is down. I followed those instructions, had no apparent difficulties, brought PSM back up, and the price-history graphs still show that one extreme value in July that make the graphs useless at this point.

I refreshed the prices numerous times, both all-at-once and one-at-a-time, and in no case did that straighten out the history. Am I missing something? Were the instructions above designed to cure this problem with historical quotes, or is that a different problem?

Thanks for any help available.

No, neither the DLL nor new version of the software will fix historical quotes. It will only filter out new bad data coming in.

You can force a re-download of the historical data (assuming the data is available from Yahoo) by right-clicking in the chart and selecting Options->Re-download Chart Data. (Keep in mind that Yahoo does not have historical data for all tickers, so this may not work.)