Amen to this post! I also noticed the issue of incorrect, unreliable information on the Stocks widget, and so I don't trust it. What a bummer, because it's such a good idea, and I am surprised more people have not raised this issue.
Here is my experience: When I check my price quotes after the US markets close, the prices displayed for my stocks and mutual funds are correct, but the daily price changes (ie, the plus or minus numbers) can be incorrect, and these daily price changes fluctuate almost every time I click in and out of Dashboard.
Before you say, "Duh, that's just after-hours trading moves," remember that regular mutual funds do not trade after hours, so the daily price changes should be constant after the markets close. As for stocks, the daily closing price is given on the Stocks widget and does not change, so the daily price changes should not, either.
From trying to divine the reason for these unfixed daily price changes, I noticed a pattern: that the price changes tend to show either the real daily price change (ie, the correct result), or the sum of the last two or three days' worth of price changes. Believe me, it didn't take long to see this pattern, so no, I didn't waste much time wondering and I do have a life.
So, what is the answer, Apple and quotes.com, or other Stocks widget users? Why can't I get accurate, fixed daily price changes? The flucuations make me second-guess the closing prices, so I tend to rely on other sources for quotes. Again, what a bummer!