I am curious why you are grouping on LastContact and not ComputerID?
Totally off the top of my head, perhaps something like this will work:
spjobs.ComputerID IN
(
Select
spjobs.ComputerID
From
spjobs Inner Join
computers On computers.ComputerID = spjobs.ComputerID Inner Join
locations On computers.LocationID = locations.LocationID
Where
spjobs.Status <> 9 And
computers.LastContact > Date_Add(Now(), Interval -15 Minute)
Group By
spjobs.ComputerID
Having
Count(spjobs.Status) > 2
)
Totally off the top of my head, perhaps something like this will work:
spjobs.ComputerID IN
(
Select
spjobs.ComputerID
From
spjobs Inner Join
computers On computers.ComputerID = spjobs.ComputerID Inner Join
locations On computers.LocationID = locations.LocationID
Where
spjobs.Status <> 9 And
computers.LastContact > Date_Add(Now(), Interval -15 Minute)
Group By
spjobs.ComputerID
Having
Count(spjobs.Status) > 2
)