I had the same problem a lot of people report here: Crashes and the annoying message the the paged pool memory is at its limits. I think I found a solution because I'm at mission 18 now and did not experience any more problems. In my Windows XP boot.ini there was the /3GB option enabled. Windows did this automatically because I have more than 3GB RAM. This costs a lot of the paged pool memory. After removing the option and a restart my paged pool memory size more than doubled from 150MB to 360MB. Starcraft worked without problems afterwards.
Interesting, I want to see if anyone else can verify this. To modify your boot.ini file, the easiest way is to right click on my computer and select properties, navigate to the advanced tab, and choose "settings..." under startup and recovery and select the option to open your boot.ini file. (Hope that's right, cause I'm going on memory for XP XD)
