One thought is if you're using USB modems. For some people they can cause unreliability issues. Scroll down to 3.4 on this link: 3.4 USB-based modems/routers

* See Downlds stopped/slow down.

To limit the stress on your computer, do not Resume all your files. This will definitely cause problems potentially as bad as yours.

Limit uploads to 70-80% : Tools>Options>Uploads>Basic
Go to LW's menu Tools>Options>Speed & tick Disable UP Capabilities & press the Apply button.
Delete some of the old incompletes that are 0% in your incomplete folder. Do the same for your Download window in LW.
Go to LW's menu Tools>Options>Downlds & tick Auto-clear downlds.
Either keep your simultaneous downlds to a minimum or reduce your downld speed so you have some left over for browsing: Tools>Options>Downloads & reduce to about 90% & press Apply button.

Go to menu View>Show/Hide & hide/close all the LW windows you're not using at that time. eg: Connections, Monitor, & Library windows.

Close search results that are more than a few hours old.

Don't use LW's media player, but instead use your own player. Tools>Options>Player & untick option box & press Apply.

Alternate players: 1. QCD is free & has inbuilt codecs & plays everything OR
2. iTunes (also inbuilt codecs & is free) which arranges music into artist & then album sub-folders (but might use a little more ram.)

Hope these suggestions help. They will all reduce both stress on LW, stress on your cpu & ram & your bandwidth.