Every time I run pro tools my computer crashes and says BAD_POOL_CALLER?

My computer will download the software, but when I try to save or open a session it crashes and I get that damn message. I am Using a Sony Vaio from 2002 w/ a pentium 4 processor and I have 2GB of RAM which is plenty. I've used Pro Tools on this computer before but I just got it fixed and now it won't work.