As mentioned here:
There are issues when marking a feed to not update anymore.
In 1.6 I am finding that most, if not all, of the feeds I have marked with Update frequency 0 (and verified in the subscriptions.xml file) get reset to 1440 the next time I start RSS bandit. This is happening for individual feeds, as well as a whole folder of feeds where each one it marked with a 0 update frequency, then the folder is marked with a 0 update frequency.
1440 (24 hours), is the default setting for Tools->options->Feeds.
This may be the same as http://sourceforge.net/tracker/index.php?func=detail&aid=1864305&group_id=96589&atid=615248
If that is the case, then the bug is not fixed in 18.104.22.168