Redmine

Hi all,
I am running currently stable version of Redmine (1.2.1) on my minimal server. I am trying to periodically check new commits using external script as mentioned in FAQ (http://www.redmine.org/projects/redmine/wiki/FAQ#Commits-dont-show-up-in-the-activity-until-I-click-on-Repository), but sometimes I get error that svn --xml couldnt allocate memory. It is quiet weird for me, because if I leave "Autofetch changes" option in "Admin" section checked, it works perfectly (but it is not periodical and it takes some time to fetch commits). I tried ruby and rake version too, but I get same error (my server is running 190MB of RAM, Redmine works using WebRick for now). Is there an intelligent way how to solve this problem and why it occurs only if I fetch changes using external script?

Another question about repository fetch: I fetched changes, but after that log messages were changed in my SVN tree (using pre-revprop-change). Is there a way how to completely refresh commit logs? Simple fetch commits doesn't work for me.

Thanks a lot for every answer!