I drugged the president and convinced the doc to release the virus but I can't get to the reactor (level 4), walkthroughs say the way is behind the presidents office but I only see a very small rectangular room opposite some droids, it won't allow me to enter the room at all.
Any ideas?...sooo close to the end :(

http://fallout.gram.pl/maps/enclave05.jpg
http://fallout.gram.pl/maps/enclave04.jpg
Maybe this will help you. I dont remember right now which door lead you do Frank Horrigan.

Its ok, i figured out the problem, i was using the walk pointer instead of the arrow pointer on the room.
Thanks anyway.
Now i'm stuck trying to get the turrets to attack horrigan, i have the presidential pass key but i cant log into the system :(