Let's start with a grid
N - Prof - Stud - Area
1 - [ABCD] - [PQRS] - [FHMS]
2 - [ABCD] - [PQRS] - [FHMS]
3 - [ABCD] - [PQRS] - [FHMS]
4 - [ABCD] - [PQRS] - [FHMS]
Apply rules 1 (R first) and 4 (Systems last), they're quite straightforward.
1 - [ABCD] - [ R ] - [FHM ]
2 - [ABCD] - [PQ S] - [FHM ]
3 - [ABCD] - [PQ S] - [FHM ]
4 - [ABCD] - [PQ S] - [ S]
Since B works in finance (2), his student can't go last.
1 - [ABCD] - [ R ] - [FHM ]
2 - [ABCD] - [PQ S] - [FHM ]
3 - [ABCD] - [PQ S] - [FHM ]
4 - [A CD] - [PQ S] - [ S]
Student S is in HRM (5):
1 - [ABCD] - [ R ] - [F M ]
2 - [ABCD] - [PQ S] - [FHM ]
3 - [ABCD] - [PQ S] - [FHM ]
4 - [A CD] - [PQ ] - [ S]
B is immediately after C (6) - B can't be first, C can't be third or fourth.
1 - [A CD] - [ R ] - [F M ]
2 - [ABCD] - [PQ S] - [FHM ]
3 - [AB D] - [PQ S] - [FHM ]
4 - [A D] - [PQ ] - [ S]
Remember that B is in finance, leaving 1 = R = Marketing.
1 - [A CD] - [ R ] - [ M ]
2 - [ABCD] - [PQ S] - [FH ]
3 - [AB D] - [PQ S] - [FH ]
4 - [A D] - [PQ ] - [ S]
Since D is P's professor, he can't be R's.
1 - [A C ] - [ R ] - [ M ]
2 - [ABCD] - [PQ S] - [FH ]
3 - [AB D] - [PQ S] - [FH ]
4 - [A D] - [PQ ] - [ S]
Now, let's try trial and error quickly:
Assume 1 = A
1 - [A ] - [ R ] - [ M ]
2 - [ BCD] - [PQ S] - [FH ]
3 - [ B D] - [PQ S] - [FH ]
4 - [ D] - [PQ ] - [ S]
C can then only be 2, which leaves B 3 and D 4.
1 - [A ] - [ R ] - [ M ]
2 - [ C ] - [PQ S] - [FH ]
3 - [ B ] - [PQ S] - [FH ]
4 - [ D] - [PQ ] - [ S]
D is with P; B works in Finance; S is in HRM.
Solution 1
1 - [A ] - [ R ] - [ M ]
2 - [ C ] - [ S] - [ H ]
3 - [ B ] - [ Q ] - [F ]
4 - [ D] - [P ] - [ S]
Aha, a solution!
Now, let's see if 1 = C works:
Assume 1 = C
1 - [ C ] - [ R ] - [ M ]
2 - [AB D] - [PQ S] - [FH ]
3 - [AB D] - [PQ S] - [FH ]
4 - [A D] - [PQ ] - [ S]
B is immediately after. Remember he's in finance.
1 - [ C ] - [ R ] - [ M ]
2 - [ B ] - [PQ S] - [F ]
3 - [A D] - [PQ S] - [ H ]
4 - [A D] - [PQ ] - [ S]
S is in HRM
1 - [ C ] - [ R ] - [ M ]
2 - [ B ] - [ Q ] - [F ]
3 - [A D] - [ S] - [ H ]
4 - [A D] - [PQ ] - [ S]
D is with P
Solution 2
1 - [ C ] - [ R ] - [ M ]
2 - [ B ] - [ Q ] - [F ]
3 - [A ] - [ S] - [ H ]
4 - [ D] - [P ] - [ S]
Well, that's another solution fully consistent with the rules. Turns out this puzzle has two correct answers.