A little investigation told me that CE2 page 11 is not innocent. Instead of player enters "room elements" it's player enters "empty space" on that test level. So when player enters empty space, CE2 page 11 is triggered, which in turn triggers CE12 page 1 (special steel wall changes to empty space).
And CE12 page 1 is also triggered when CE2 page 1/2 is triggered, so the steel wall disappears when the room creation progress reaches the right/bottom border.
And because the outer playfield is so big, CE6 has so many creations to make, which causes an "endless" loop (but I'm pretty sure that it isn't endless, but somehow it's wasting resources.)
I have another level here which proves this:
http://www.zomis.net/rnd/download.php?id=623
EDIT: The level should be tried with the pre-release 3.2.3-0
Enlarge playfield to 128x128 to make RND crash
Make the playfield smaller (like 18x18) to see that the creation goes much faster (which is natural, of course) and that Rockford responds more quickly when you press a key to turn him around.
Another interesting bug which can be seen in the level above:
Turn off the "creation of" condition for CE1, and change replace when to "destructible" and you will see that only 4 rows of CE1s will be created, the first 2 rows will have 8 CEs and the next 2 will have 6 CEs. This is probably because the elements overwrite each other when changing, but I still think that it's quite odd behavior... but I don't know how to make a workaround for this (except making the element indestructible or change replace when to something less than "destructible").
EDIT: The level should be tried with the pre-release 3.2.3-0