Hi,
If you mean the mojoPortal log, it is just a text file /Data/currentlog.config
If it can't clear the log, that means it has not enough permission to delete the file or clear its contents. If it has some things already logged then either those things got loggedon another machine before deployment or file permissions have changed after deployment.
I don't know if the blank page problem (I have not seen this problem) could be related to the file permission problems but possibly.
When I visit your site it seems to work as expected, I don't see any blank pages.
Hope it helps,
Joe