I am having problems with PHP memory allocation, it's been a while but it's back!

Funny thing is that the site works fine when not logged into the system. It's only when logged in, that I have problems. But even in that case, one of the template pages (FULL) can be viewed and edited while the other one - Right Sidebar - is throwing the PHP Error.

To troubleshoot this issue, I have tried to following:

1. Restore all site files (because the problem occurred when I made a change to a theme file).
2. Restore the theme.
3. Clear the Cache.
4. Restore affected pages to previous versions.
5. Add an .htaccess file with this line - php_value memory_limit 128M;
6. Add the following after the PHP opening line in the index.php file - ini_set("memory_limit","128M");

#5 and #6 resulted in a 500 Server Error - so I undid those.

The hosting company support team investigated the problem and this was their response.

We've accessed the admin area and reproduced the error. We temporarily had the memory limit increased from 200 MB to 400 MB for testing. That made the back-end load slower, but ultimately it resulted in the same error (only indicating it had tried to use the more memory we had allowed).

This leads us to believe there must be some internal condition that isn't met, and the script retries indefinitely some iteration that depends on it, until the process hits the memory limit.

This appears to be related to the application itself. We suggest you try and reinstall the theme, if that is an option. If you recall the exact modification you had made, you could try making sure it is reverted. You could also check with the theme developer if they are able to investigate this matter.

I am trying to redo the theme ... anyone have any other suggestions!

P.S. The error occurred when I was making an edit and trying to save it. I got the little working icon/gif and it wouldn't quit. Ugh!