There are tons of reasons services could fail to start in windows NT. Do you have any idea what the vadatant service might refer to? Do you have any program installed that has a similar name?
Most likely its either hardware or software that you installed/uninstalled/deleted recently.
Basically NT is trying to run a program that doesnt exsist.
If you can't figure out what NT is tryin to run but it hasn't effected anythign else, then just disable that service. Start / Control Panel / Services /
find that service and set its startup state to Disabled or Manual