I had a paid support case open with Microsoft. We have the Backup Exec Agents installed on all of our Windows Server 2012 Hyper-V hosts.
When running "fltmc" at the command line, according to microsoft "virtfile" is an incorrect decimal altitude. Not only should it not be a decimal value, but it is loaded in the reserved range for Microsoft drivers , which is 420000-429999.
They said to check with Symantec immediately on this.
C:\Windows\system32>fltmc
Filter Name Num Instances Altitude Frame
------------------------------ ------------- ------------ -----
VirtFile 0 429999.280700 0
Also your dropdown for "Operating System on which product is running" for this forum doesn't included Windows Server 2012. Might want to update that.