I bought my PCM-M10 from Musician's Friend back in December 2009 and it hasn't skipped a beat. In fact, I'm still running on the first pair of lithium AA's. At any rate, I've put it to the test by removing the batteries for a week and after reinstalling the batteries, the clock was still intact.
The poll is hardly a fair one and to better determine how massive this issue may be, it should also have the option of "No, my unit is fine from day one."
At any rate, for those of you experiencing this problem, good luck with resolving it. Hopefully it's still too minor an issue to overshadow the real benefits of this recorder. Perhaps I should look for a screen protector for it as well even though it's still in pristine nick.