Recently I installed the 'treewalk' dns program and I ran BD 10 freeware a couple of days later. BD picked up on instsrv.exe saying it was virtool.2041 and deleted it.

I had to delete treewalk and reinstall it after that was deleted. Instsrv.exe is back and I have found some posts in the Kapersky forum and the Treewalk forum saying that it is necessary for treewalk.

Dear sir or madam,
This file is detected as Virtool. This means that it may be used for malicious purposes. This detection stands.
If you know it is there for a valid reason you can except it from scanning.
Thank you.