DS4000 paperweight? - Horizontal scale problem

[Circuitous]

I've been using my DS4024 for 8 months now and this evening, after only being on for an hour, the horizontal scale control stopped working.  I can press the hated AUTO button, and it will set the timing properly on a test signal, but I can't change the setting manually.
I tried the two methods for resetting to factory default and disconnected the power for a while, but no luck.
The system info indicates the outlet temperature as 35.5 C, room ambient is 22.7 C.  35.5 doesn't seem particularly warm.  I haven't made any changes in my bench layout, etc for months... it just stopped working.

Has anyone experienced anything similar?

[TooOldForThis]

Just some stuff to try...
When you push the scale button in, does the screen change to the split view?
Under the horizontal menu button, are your options Delayed=Off, Time Base = Y-T, ScaleAdjust=Coarse, HorRef=Center?

If you change ScaleAdjust to Fine, does the scale knob have any effect?
Does pressing the orange Default button return return it to normal?

[Circuitous]

Yes, I tried the default button, and the trick of forcing defaults at power-up.
Pressing the horizontal scal knob puts it into zoom mode, but turning the knob doesn't have any effect. 
It could be a hardware fault, but just seems so odd.

[grego]

If it's 8 months old its still under warranty - just send it back to Rigol for them to fix.

[Circuitous]

I sent an email to tech support about 2 hours ago.
I just got a call from Joel at Rigol, says it doesn't sound like a firmware issue and they'll send me an RMA.  They expect that it will take a week from the time I ship it, until I get it back.  That would be pretty quick service.

[echen1024]

I traditionally just let warranty handle these issues. Is the rotary encoder good? Other than that, I can't think of anything else. And 1 week is pretty quick. It's about the time Lenovo took to fix my ThinkPad.

[saturation]

Have you tried resetting the scope to factory, then do a calibration?

[Circuitous]

I tried the default function, didn't recalibrate it.  I checked with Rigol support, the didn't have any other way to reset/default it.

[Circuitous]

Just following up on the problem.
I shipped the meter back to Rigol on Friday 7/26 and they received it on Tuesday 7/30... then it languished.  after about 10 days I sent a note... no reply.. sent a note agin the next day and received the reply that the usual guy who works on the DS4000 units was out for several days.
Unit returned on Tuesday 8/20.  So, 3 weeks instead of 1 week... a bit annoying.  But, they were easy to work with, no hassle about the warranty or anything.  And, the past month has been vacation season here, with very few people around my office.
Also, they upgraded the firmware to the latest 00.02.00

The SPI decode seems to be working nicely again.