I have Sony Experia Arc. It worked fine on windows 7 but now, since I've installed Ubuntu 12.10 My p.c. doesn't detect my phone.
I found that the error is a kernel version 3.5 that uses Ubuntu 12.10. I just tried the Ubuntu 13.04 dailybuild of today (January 27) that uses the kernel version 3.8.0-2-generic and the problem has been fixed. So the only solution I see to this problem now, is moving to Ubuntu 12.04 which worked perfect or wait for the new version of Ubuntu comes out in April.
[UPADTE] With the latest update of the kernel, the problem was solved and the phone connects perfectly