Forgot to mention that my responsibility was implementing IPSec on the network. It was interesting how many things I got blamed for... from making the computer's too slow to BSOD'ing them to "breaking everything". Only about 25% of the time it was actually an IPSec-related issue.
We were effectively using IPSec as a host-based firewall, though an actual firewall software would have worked a lot better (IPSec is not meant to be used this way).