500 Internal Server Error

[geomouchet]

I'm trying to convert from YABB SE.  The converter runs for a few seconds, goes through a few steps and then gets a 500 Internal Server Error.  This is what is displayed right before the error:

Converting...
Converting members... Successful.
Converting categories... Successful.
Converting boards... Successful.
Converting topics... Successful.
Converting posts (this may take some time)... Successful.
Converting polls... Successful.
Converting poll options... Successful.
Converting poll votes... Successful.
Converting personal messages (step 1)... Successful.
Converting personal messages (step 2)... Successful.
Converting topic notifications... Incomplete.
Not quite done yet!
This conversion has paused to avoid overloading your server, and hence not working properly.
Don't worry though, nothing's wrong - simply click the continue button below to start the converter from where it left off.

How do I proceed from here?  I can go back and re-run, but it always fails in the same place.

[geomouchet]

My web host checked the error logs and said I was running out of memory.  They increased the limit. Is it re-runnable or do I have to truncate any tables first?  When I tried to rerun it I got this error repeated many, many times:

Converting attachments...
Warning: feof(): supplied argument is not a valid stream resource in /home/bushpilots/www/www/smf/convert.php(1109) : eval()'d code on line 20

Warning: fread(): supplied argument is not a valid stream resource in /home/bushpilots/www/www/smf/convert.php(1109) : eval()'d code on line 21