隱形檔 question~

Don't know why, i got a few microsoft office document being mutiplied by the computer.
for e.g.
Original name of document: HelloK
The "copied" document name : ~$JSHelloK

It's like when you open a file, you saw 2 documents.
One is HelloK. Another one is ~$JSHelloK, and it is a 隱形檔 also.
Is it virus infection?
Plz help!