Sandisk Cruzer Switch 32GB problem -- drive empty or suddenly vanish when copying file

I have strange problem with my new SanDisk Cruzer Switch 32 GB. Sometimes I have to plug, remove, plug, remove, plug again then the disk is listed properly on My Computer. --> By ‘My Computer’ I am saying the label Windows generally used. Properly means, I can see the contents, and My Computer showing the disk label, the free GB and full capacity in GB. If I did not remove the device, the drive letter may be assigned, but no disk detected. The very same kind of thing happen when you use a memory card reader but without the memory card inserted. Other case is when I copy file into the disk, maximum transfer rate is 3.8MB/s, while using other flash drive I can get more than 10MB/s. Another strange thing, already happen three times, when I copy something from the flash drive, the process stuck, then the disk is gone. The drive letter is still exist, but without the disk. If I look at My Computer, the drive letter is still assigned, but no disk in it. Properties showing 0 byte used from 0 byte available. What is the problem?

SWAGs (Some Wild-Ass Guess)

Dirty/oxidized USB contacts on plug and port.  

Low voltage, either to the USB hub or from the machine’s power supply. 

PC virus.