I found some info in german. It mentions: installed a Sync-Tool for "Windows Mobile", XTNDconnect and sybase, does that mean anything to you? They would be log files.
they don't mean anything to me unfortunately I use Dropbox though, hmmm if I edit the files with Notepad ++ all there is in there is NULNULNULNUL
Normally they are Error Log files related to: ADT = AdvantageTable ADI = Advantage Index ADM = Advantage Memos Use ARC to read the log, open the ADS_ERR.ADT table
Also found these files on my computer. Just opened "ads_err.adt" and found strings like; C:\Users\<MyUserName>\AppData\Local\Research In Motion\BlackBerry Desktop\XCPCSync.OEM\SyncSDK.209.601\Data\TransContract.adiI So in my case it was the Blackberry sync software from RIM (Research In Motion) that left those files. Deleted all RIM software recently anyway for obvious reasons... no more BB for me...