[imdarkside]

see if your phone is going into sleep mode. if you installed s2u then have it stay on (battery charge mode) when tethered otherwise find the setting that keeps phone from nodding off when tethered. i noticed same problem in past but cant remember exactly what I did. it definitely was that the phone was going into sleep mode and lost connection to the pc. it was a real easy fix. no reflashing needed for me to fix this prob. may need to check activesync settings or phone settings but it should be easy to resolve.