The first step is to do a System repair... this is carpet bombing i Know, but the thing is that you say that other Xperia U's next to you connect fine... so please do this to rule out that you have a software issue.
Here are the steps:
Run the Pc companion Software (http://www.sonymobile.com/us/tools/pc-companion/ )
Turn the phone off and disconnect it from the computer
1. No matter what the program says do not connect the phone until you complete step 9
2. In the welcome screen if asked click on start, Next you will be shown what media go offers, click on "next" then you will see a presentation on what support zone offers, click on "Finish"
3. In the next section from "support zone" and "media go" new select "support zone" and click on start.
4. On the next page select "Software update" and click on "start"
At this point if you get an error stating that "unable to install update components" or "server is busy" Please proceed to step 12
5. The program will say that there is no phone connected and will ask you to connect but disregard that and instead choose the option to "repair Phone".(the program will issue you a warning on the content that you will lose during the update)
6. Choose the option to continue.
7. After that, the program will download the necessary information (5 to 6 minutes) and it will present you with a list of phones.
8. Choose the Phone from the list (close to the bottom of the list) click on the icon for the phone and then click on "next"
then you will see a new section telling you how to connect the phone. (don't connect it yet)
At this point the phone must be off and disconnected from the PC.
9. Connect the cable to the PC not to the phone, then follow the instructions on screen to connect the phone, if done correctly the program will say "the update of your phone has started..." (in some cases a message of "Installing drivers" will appear before the message of "the update of your phone has started..." is shown.)
10. If you failed to follow the steps correctly the phone will turn on and it will request that you "Proceed with the following steps, slide down the notification bar", If this happens disconnect the phone from the cable, turn it off and repeat from step 9).
11. If the PC Companion proceeds correctly wait for the update to finish and follow instructions on screen.
Dear customer,
12. If "unable to install update components"
1. Close Pc companion
2. Install Java from: http://www.java.com
3. start Pc companion again and try to do the software unlock process once more.
After doing this then check if the phone connects properly.
Let me know what happens.
Francis.
