I think Lennart is probably correct with the reference to the thread on memory issues. PSP sieve units have among the largest memory footprints of all the applications (more then 150mb per unit), whereas the AP26 units (that you have run without error on that machine) have the smallest footprint (around 2mb or less per unit). Given that you would be running 4 workunits at a time, and likely would have many other things in memory (e.g., AV software, open browser, etc.), the PSP sieve units are probably pushing you over the 2GB threshold into the second bank of memory (I am guessing that your memory config is either 4x1 or 2x2).
You might try swapping the memory around to see if you can get start-up errors when putting the memory from the second bank into the first to identify the potentially bad memory.
141941*2^4299438-1 is prime!