ActiveSync disconnects

I just got a Pocket PC (a Toshiba e330 XScale) and ActiveSync often disconnects for no apparent reason. I have to get the PDA out of the cradle and reinsert it to make it sync again. Sometimes it's even worse and I have to reboot the computer to get things working (or else Windows reports a USB problem). In all cases the PDA continues to work normally, but it can't sync. I use the USB cradle that comes with the PDA and ActiveSync 3.6. I never use 3.5 though, so I don't know if it was better. Is there any solution to this problem?