Nbtscan.exe is an open-source tool that Spiceworks embeds in their products to help discover devices on their network, but is detected by WFBS as HKTL_NBTSCAN.
WFBS gives this detection because it recognizes this tool as a grayware, which can be used maliciously to gather information.
To resolve this issue, you need to add the Nbtscan.exe application to the antivirus/antispyware scan exclusion list. For instructions, you can refer to this KB article: Configuring exclusions in Worry-Free Business Security (WFBS) File, Folder, and File Type Scanning.
There are other applications that are recommended to be excluded from the WFBS scan. You can refer to this KB article for the list: Recommended scan exclusion list for Trend Micro Endpoint products in Worry-Free Business Security (WFBS).