Thanks all!
@Bob:
I checked the program path in the shortcut just in case, and no, it's not going to Program Files x86 (come to think of it, I didn't install the 32-bit version).
@John:
The shortcut is indeed NOT running Sonar as administrator, but that is because I read in the X1/X2 reference guides that Sonar doesn't need to be run as administrator anymore (I admit I know little about PC settings and don't know the advantages/disadvantages of running a program as administrator. One thing I noticed when I didn't ran another daw as administrator is that it failed to detect IK Multimedia plugins). Anyway, I just checked the Run as Administrator in the shortcut and now it seems this personalization message stopped appearing. But I need a few days to be sure it's really gone. When I was on the 32-bit OS I never ran Sonar as administrator but didn't get this message so often (only once in a blue moon). Strange.
@lawp:
As I said, I've been using Ctrl+F10 for quite a while (more than a year) to launch Sonar and rarely saw the message to appear. But I just changed the shortcut key to just F10 and launched X2 (disabling the Run as Administrator) and it also stopped showing the personalization message. But again, I need a few days to be sure and determine what the real cause was. I think the mod that triggers repersonalization is hold CTRL+SHIFT and double-click on the SONAR icon, no? That's what tech support told me.
Thanks all again. :)