Do you also got warnings about too many processes?
I had a series of problems where I couldn't open applications and it would sometimes bring up that error, in the end a fresh install sorted it out. There were a couple of things that sort the problem however only very briefly. A reboot would allow me to use some applications but then the system would get into a state where it would bring that error up rather than the applications. I guess yours is worse as it is bringing down Finder as well.
For me the problem started after a kernel panic, have you had any crashes before this? System power failures? Are there any messages in your console/crash log that you can access?
You could try reapplying the latest update, didn't work in the long run for me but always worth a shot.