Make sure you're using at least Java 1.5
You can find out by going to LW's menu bar, Help menu > About LW & it will show both the LW version & the Java version.

Also reduce your upload speed to about 80%.
Go to Tools>Options>Speed & disable Ultrapeer capabilities.
Go to Tools>Options>iTunes & disable all iTunes options.

When you open LW, let it settle before doing anything. Wait at least 10 mins so your shared files have loaded properly, & your incompletes have both loaded & attempted to connect on their own. Then use the search function, etc. If you use the Resume/Find Sources function, don't apply it to all files at once! Only apply it to 2-3 files at one time. Otherwise that can have side effects such as use up too much resources for LW, your computer & modem.

Also, if you have an ethernet card, use that rather than use a USB connection to your Belkin. USB tends to draw both power & CPU from the computer & doesn't handle high/heavy traffic very well.

If you have over 1,000 incomplete files, then consider this: Tip: Purge the Downloads Queue! & apply it to those files with 0% downlded.