My Rezound has been getting progressively worse in this respect. It's a very strange thing that used to rarely happen, but now happens about every other time I try to unlock.
It seems like the phone has lost track of real time, and is behaving as though time is moving much faster. I say this, as the behavior I observe is:
As I draw the unlock pattern on the dots, after the first two dots it stops to tell me that I've drawn the pattern incorrectly (even though I'm still drawing), then it picks up two more dots from later in the pattern to tell me I've done it wrong again, then moments later it shuts off the screen. It should normally take it about 30 seconds for the timeout to shut off the screen, but here it's done in about 6. It seems like it thinks time is moving about 5x as fast as it really is, and it is timing-out the unlock trace as well as the screen lock waaaay too fast.
Used to be, if I hit the power button again to turn on the screen, it would work fine the second time. However, over this last weekend, I have noticed that it gets stuck in this mode until you hit the, "You've drawn your pattern incorrectly 10 times. Please wait 30 seconds," error. Then, I can unlock after 30 seconds.
What I have done as of yesterday is to switch to a PIN (numerical) lock rather than using the dots. So far, I have not experienced any problem with that.