LW 5 groups similar results together by default... so you might not see as many single results as usual?
Check out this info: Options - LimeWire

So you could go to LW's tools > options > search > untick 'group similar search results together' > ok.
See whether that makes a difference.

Changing the ultrapeers that you're connected to can also effect your search results.
Click on Advanced tools & you'll see a list of hosts (ultrapeers) that you're connected to. Right click on the host that has the longest connection time > remove. See whether that makes a difference to search results. If not then try removing the host with the next longest connection time & so on...