Hello,
well, seems that more memory than your site has allowed to use is required to display the page in question.
Basically, you have 2 options:
I. increase the set memory limit (you may need to contact server admin
to do so); now it seems the limit is 26MB, you may need at least 32MB, 48MB or
64MB. (we are ourselves running sites that need even 128MB)
II. you will need to optimize the site - that is theoretically possible,
but may take quite long and the result is not guaranteed (basically this
would mean decrease number of items that are loaded at once, such as
number of items shown on HP, number of items in menu, limiting
generation of all menu levels, etc., etc.)
Also, in both cases, consider using some more caching.
If possible with your hosting provider, I would certainly apply for 1)
Requiring 64MB for your site is nothing bad. If you would have problems,
I would advice to change the host.