Running cron failed and show white page I am using Drupal 7.

When I am running cron manually as an admin, I get white page. 
When I am looking at the dblog report immediately after trying to run cron, I always see the following notice:

TYPE    job_scheduler 
DATE    Monday, March 17, 2014 - 00:15
USER    Guest (not verified)
LOCATION    http://www.site.com/admin/reports/status/run-cron
REFERRER    
MESSAGE Finished processing scheduled jobs (0 sec s, 0 total, 0 failed).
SEVERITY    notice

It is also strange that the user of this activities is "Guest (not verified)" and not Admin.

Yesterday I made alot of changes and installed some performance module as the boost module, file cache module and advagg module. But I always run cron after installing a module. 
After few tests and enabling/disabling modules, it looks like that the problem is the filecache module

Can someone help me solve this issue?
Hard to debug without further details.
If you get white page then check your Webserver logs, especially error log.
You can also try to run drush cron to catch some more details (error messages).