If you're using PDO on Windows and fetching multiple records crashes apache, you are probably using Xampp (1.7). In that case, go ahead and update your PDO dll file... Or update the entire Xampp environment, while you're at it...
This does not affect linux environments and probably not even Windows PHP without Xampp.
Hope it helps ya... it took quite a few annoying bug reports to figure it out. Of course right after I found it somebody else tells me about it... :)