(Right thread this time...)
As an alternative to the others, you could do it by adding a registry key to each the computers and checking for that key during the load process. Set the key to one of a preset range of values (long random keys if more security is required), with each key giving access to a certain level of loading e.g. "LOAD LEVEL A" for the main group, "LOAD LEVEL B" gives access to the base plus loads extended capabilities, "LOAD LEVEL C" gives access to everything including diagnostic tools.
Could be a little more useful if you have high turnover - keeping up to date on all the valid login IDs can be tasking.
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If you are going to fly by the seat of your pants, expect friction burns.
"I don't know" is the beginning of knowledge, not the end.