If you know how to use a mac I'm not sure why yo should have these problems. It sounds to me like you had LW's Ultrapeer setting set to on. It also looks as though you had all other setting set to maximum. That's why all your bandwidth was used up. Also keep in mind within OSX there's a Java issue with ram.

Suggestions: Go to LW's Preferences & make these changes:
1. LW's Prefs>Speed & tick the option box for disable ultrapeer abilities.
2. You may also prefer to set your connection type to a lower setting so you have more control over it.
3. Prefs>Downloads: Set your dwnld bandwidth to less than 100%; eg: 75-90%
4. Prefs>Uploads>Basic: Set uplds to a % that allows you to be able to browse in the background.
5. See these hints about optimising LW: A well set-up LW can start to automatically continue its dwnlding after it's settled down perhaps 2 out of 3 times you open LW. Optimising LW & Maximising Uplds & Dwnlds A (1st post only) & also Part B which is even better & last & least are search & dwnld hints. The latter one I've been thinking about re-writing for some time. That's just for playing it safe. eg- I show all speeds & qualities.

Now your upld & dwnld will allow you plenty of bandwidth for browsing, etc. UP will definitely use up bandwidth as it means other people will go thru you to obtain connections.

To reduce ram use close LW's windows you don't need open. Also get rid of obsolete searches & even hide LW in the dock.