U3011 Input Source question

Hello,

I have a Dell U3011 (still in warranty) and I'm seeing a problem.  I contacted support and they said something that just doesn't make sense to me.  While they're going to work on the issue, I'm coming here to better understand their (initial) stance.

Background: Until recently my setup was:
DVI-1:  Dell Precision workstation (quad core)
DVI-2:  Dell Precision workstation (dual core)
HDMI-1:  Sony PS3
HDMI-2:  Comcast DVR

During this time I was able to switch between these four inputs without any issues.  Everything was chipper. In July, I gave the dual core system to my better half.  Everything continued to work like a champ. About two weeks ago, my Son wanted to connect his Dell XPS 15 (L502X) to a new Vizio 47 inch 3D HDTV.  As in robbing Peter to pay Paul, I borrowed the HDMI cable from my Comcast DVR and gave it to him. I'm now seeing the following issue:  When I switch DVI-1, HDMI-1, and back to DVI-1 the upper left hand corner of the monitor and the lower left hand corner of the monitor OVERLAP each other and flicker.  The ONLY way to stop this is to TURN OFF the monitor.  While this is a workaround, the problem I have is I'm using the USB ports and USB card reader.  Turning off the monitor causes issues with the various USB devices.  What got me off my duff and look into the problem was when one of my 2.0 TB drives wouldn't eject and after doing the power cycle of the monitor, I had to wait 2 hours for a check disk on the drive (before Windows liked it again). OK, that's the background.  Next comes my issue and why I'm posting. When I called Dell support (the monitor is still under warranty), I'm told the proper way to switch between input sources is to turn the sources and then do the switch and then power the input source back on. Ah -- I have a couple of issues with this requirement.  First, I don't believe it given my past experiences.  Second, this requirement would defeat being able to work on two computers at the same time.  You'd be turning them off and on each time you wanted to check out the other computer.  Third, if you want to check out something on TV and then act upon it quickly (e.g. stocks, etc) you'd be .  Fourth, I've seen other people using the Dell U3011 switching without powering off their input sources. I went to the Dell website and found the various web pages, which make up the user's guide.  I read them (even downloaded them, so I could read them later).  I couldn't find and still can't find anything in them saying I need to turn off my computer in order to switch away or back to it. Is the Dell support person right?  Is he wrong?  Oh yes, I've found some Dell support persons don't know what they're reading and/or saying.  I've also found some who are very smart and teach me lots of stuff.  (I've been at this computer stuff since 1974, BTW, starting with Wang computers (no less)). If I have to turn off the input sources before switching, where is this in the documentation?  Honestly, I haven't found it yet.
Bert Moshier
A (for the most part) very happy repeat Dell customer for the last 14 years.