Installing FSX freeware scenery when running W7 requires a slightly different method compared to when running XP. Read my second post in this thread:
http://flyawaysimulation.com/forum/topic/37376/cannot-find-add-on-scenery-in-fsx/
...I mention this for future reference.
I had a problem with UTX once - can't remember the details other than I'd installed something else in the wrong sequence/order.
The only way I could fix it was by uninstalling all of my environmental add-ons (including UTX) and later re-installing them in the correct order.
I don't think that comparing the priorities in our Scenery Library will bear fruit as we all have different set-ups. To be on the safe side and prevent making things worse I'd suggest that you too uninstall your environmental add-ons one by one. Make sure you uninstall correctly rather than simply trying to delete folders... that would make things worse.
It's a good idea to restart the computer occasionally so that the Windows OS can sort itself out. Once you're done uninstalling, run CCleaner available here if you don't already have it:
http://www.piriform.com/ccleaner
After having installed CCleaner, run
Cleaner and
Registry. During the Registry clean-up you'll be asked whether or not to backup the registry. I suggest you backup - this backup will be placed into your Documents Folder and takes up very little space.
Restart your computer again, fire up FSX and go to some of your favourite places and/or those places where you noticed strange behaviour prior to uninstalling those add-ons. Take your time with that, sleep on it before you begin re-installing again.
To avoid trouble, make a list of the add-ons you intend to re-install and make sure you read the documentation of each one before you install. If the documentation is unclear in regards to compatibility with other add-ons, google for something like:
utx and rex compatibility --- you'll be surprised what you can find.
Now if you're satisfied that there won't be any compatibility issues and you've sorted out in which order the various add-ons have to be installed, you can begin.
Install only one add-on, use it and test it thoroughly. Wait a couple of days before you install the second add-on and test again to see if there are any issues. If you proceed in this manner i.e. one by one and testing in between, it is much easier to troubleshoot and repair the damage should issues arise.
I hope you'll get it sorted