Hi, it could be a power issue.
Add max_usb_current=1 to the bottom of /boot/config.txt. This will allow the USB port to provide more power.
Some questions;
+Do you have a +2A good quality power supply?
+Is there anything else other than a keyboard or mouse connect to USB?
+Does it only happen when you are connected to the cellular network?
After you have the issue, what does the bottom 20 or so lines of dmesg look like? (paste it here)
Mark --OzzMaker.com --
