this happened to me on my K800i R1KG001 CID52 as well... i just kept trying to connect to the PC, and found that it finds it easier if you swap the USB port your using the cable under. if you get XS++ to detect the phone, you can fix it by just re-flashing your MAIN, FS and CDA files. you can also use SEUS (SonyEricsson Update Service) to de-brick your phone, but you could very easily end up with CID53, and the only way to patch / hack CID53 is with JDflasher...