16 bit ms dos subsystem

i have just started getting this error message(similar to earlier
post)c:\progra-1\vdotool\ui\biosctl.exe
crogra-1|symantec\s32evnt1.dll.
an installablevirtual devicedriver faileddll initialization.

choose close or ignore

1 can anyone offer a way to remove this error code

2 what is vdo and what does it do? do i need it on my pc?

thanx in advance