I'm using Win 7 RTM with two monitors always in use.
I've moved over from Ultramon.
After carefully sorting my desktop icons between the two monitors, a reboot has put them all back on the main monitor.
I couldn't find anything in the forums about this or any obvious setting in the configuration.
Can you please advise?

turn off DF and disable it from starting automatically, move the icons to a similar semblance of what you ahd, and reboot - and see if they stay.

if they do, enable DF and reboot again. See if they stay this time.

I found I get the same result with the latest version of Ultramon.
If I remove df and ultramon and move icons then reboot, (standard Win 7), then the icons do not stay on the secondary monitor. I wasn't expecting them to - I thought that was a feature of df/ultramon?

Looks like this is a silly Windows 7 bug. It wasn't present in Vista. It goes like this:
You have two monitors (doesn't matter which is monitor 1 and which is 2 - based on quick test), and you want the one on the right to be the primary monitor.
Windows 7 will not restore the position of icons on the secondary (left) monitor on reboot - they all jump back to the primary.
If you have the leftmost monitor as your primary, it leaves them in place on the secondary on reboot.

This is disappointing as I like having the start button in the middle of my workspace. Also, if you have the left hand monitor as the primary, you can't hit the desktop peek button without looking.

This would be a killer feature for df or Ultramon. In fact, I will buy the first one that solves this problem!

I thought it had to do with monitor positioning - thanks. This also confirms my suspicion of an entirely separate thread too.

Sorry to hear that - I think back in the day I tried having the right monitor as primary - and Windows (XP, Vista?) did not like it - Not. One. Bit.

You have dragged the monitors around in the display properties dialog box, right? Those are now drag-able anywhere - if you make your right monitor the primary, then drag it to the left of the secondary, then try your icon trick, what happens?

I'm sure that would work for the icons, but then you'd have to mouse off the right edge of your primary to get to your secondary that is on the left...

I continue to be amazed and MS's lack of any real support for dual monitors. Seems they begrudgingly make things work with the primary on the left and second on the right, but that's as gracious as they're going to be. Sad, really. The fact that W7 doesn't have a functional dual taskbar is a crime. Fortunate for Jon though.

Same issue I had with XP, though I managed a way to fix it. I'll look into it again for W7.

How did you fix it?
I have a similar problem with XP.
Monitor on right is primary (Digital), monitor on left is secondary (VGA).
The secondary monitor winds up with the icons and taskbar. I need the primary to have them.
This used to work but now after reboot everything goes to left monitor even though I have the right one set to primary in Settings. I checked the Advanced settings and it seems to be correct. The only thing I remember changing was the resolutions.

I didn't fix it - am working through a diagnosis with the UltraMon developer.