How did these strange ~$ files get here?

I am running Windows 2000 Pro on a PII 400 512K, with MS Office 2003 Pro. For the last couple of weeks I have had a list of Word documents in a couple of files that all look like:

1) ~$sume-2004-03-01-A.doc 1 KB Microsoft Word Document 9/19/2004
2) ~$sume-2004-03-04-B.doc 1 KB Microsoft Word Document 9/10/2005
OR
1) ~WRL0003.tmp 37 KB TMP File 9/25/2004
2) ~WRL0004.tmp 29 KB TMP File 12/21/2004

I would like to know 1)what set this off and 2)what setting to adjust to make it stop. I know I could just delete them all, but I am really curious and would like to get to the bottom of it. Thanks.