I've got this sentence here:
The most recent problem I can think of is personal knowledge management systems.
That seems grammatically incorrect because of the mismatch between the singular problem and the plural systems, but I can't just change it to
The most recent problem I can think of are personal knowledge management systems.
or
The most recent problems I can think of are personal knowledge management systems.
The only one that seems correct is
The most recent problem I can think of is the problem of personal knowledge management systems.
I think this equates the singular problem to the also singular problem of personal knowledge management systems. But it's extremely awkward. Any suggestions on how to handle situations similar to this?