I only wish I could be more help. This message seems to imply that the driver is still installed:
"To install the driver, please execute Uninstal.exe (located in the some folder as Setup.exe) and then execute Setup.exe once again."

Try booting up with the device plugged in. Try to uninstall it while it is still plugged in. You may be asked to unplug it and reboot to complete the installation. Then try to install it before plugging it in. You should be asked to plug it in to complete the installation process.

I've tried the order you recommended and still, no go. 

If I switch advanced driver OFF and plug in the USB cable, windows detects the device and installs drivers automatically.
I get sound this way but that's it, can't change settings etc. 
I can't even select the soundcard in Cubase 5 or Reason.

I use windows 7 64 bit by the way. 


This is so typical, I have had so much bad experience with T.C Electronics and thought Cakewalk would save me since they have 64 bit drivers but........

Do you have any other ideas? Maybe a driver cleaner program perhaps? 

I'm all out of ideas, that's for sure. Are you sure you have the right drivers? I can't get past the fact that this problem sounds like a driver error. Here are the latest Windows 7 64 bit drivers for the UA-25 EX.
UA-25 EX Windows 7 64 bit drivers found on the UA-25 drivers page . Check the "I AGREE AND WISH TO PROCEED WITH DOWNLOAD" box and click Download to see all the drivers.

I use a program (free version) called Revo Uninstaller that I like a lot. It uninstalls and deletes all associated registry entries.

Revo Uninstaller freeware

 
I am having the exact same issue with the UA-1G.  Did anyone fix this without a system restore?
 
 

Yes I agree to that this is a problem due to that something is there in the registry that is creating all this troubles. You should clear from the registry first,

Hey!

I'm not sure if you still have the problem but I just got mine working and I had the same problem.. I could use the edirol in normal mode but the advanced mode (needed for midi) on my computer didn't recognize the edirol...(Installing drivers lead to the same naver ending cycle) After a long battle...  I ran the uninstall file once more. Then I connected my Edirol UA-25 with the advanced mode on (Installing driver failed). Then I went to the "update device drivers" from the control panel. I clicked the "update driver" from the edirol driver and I chose the option to use a driver from my computer. And for the location I chose the new driver which I had downloaded from the site. Hope this helps someone with the same issues. I'm just glad I can now record midi..

Have a nice summer everyone!
 
(I have Edirol UA-25 and Win 7 professional)