USB 2.0 problem?

Hi, I have an USB 2.0 (VIA VT6202) card and storage (LaCie USB/1394-Disk Drive 10GB; Model: MK1016GAP). In 8.1, the ehci-hcd module can be loaded. But when copying large file (200 MB), the process of copying was dead after a while. And I cannot kill the process via "kill" command and the system cannnot be "rebooted" or "shutdowned". Does any body get into trouble as same as me or any solutions? Thanks in advance. Best Regards, Joseph