I have the same problem... I use MyPhoneExplorer and when I try to download files at 115200 bits/seg. the computer restarts. This only happens at home. At my job I use the same cable, the same phone, same usb drivers and the same MyPhoneExplorer and everything works fine at 115200 b/s. I think that is a hardware problem. My solution to this is to set the connection speed to 9600 bits/seg. It's slow but causes no restart.
My phone is a K300a