The web feed plugin error is filed and fixed at http://pkp.sfu.ca/bugzilla/show_bug.cgi?id=6729
; you can apply the patch there to resolve it. It's not related to this template compilation problem.
Can you post the contents of a corrupted compiled template?
FYI, one option that may correct this (at least temporarily) is to set the contents of the cache/t_compile directory read-only once they're compiled properly; this will prevent OJS from re-generating the templates and thus it will rely on the already-compiled templates. Note that of course if you change any .tpl files you'll have to relax the restrictions so that the template can be recompiled. But at least in the interim this may provide an alternative to occasionally finding the site broken.
As above, however -- what are your file permissions and SAPI configuration like?
Public Knowledge Project Team