Hi D,
There are two different errors you can run into with Form. "Out of memory" means the plug-in is running out of memory (doh!) - this might happen with a large OBJ/sequence and modest RAM config for example. This might be fixed by a reboot.
Another error is "Particle Overflow error" - this means there are too many particles (20million is the limit IIRC) in the setup. This cannot be fixed by a reboot, the number of particles need to be decreased in this case.
Peder