I had recently installed JRE 1.4, and since then Limewire has behaved strangely: when downloading files, the speed continually slows until it reaches 0KB/s. Additionally, if trying to do a search, and I hit the ENTER key, nothing happens. Only rebooting temporarily resolves the problem.

I have completely removed 1.4, and reinstalled 1.3.1_01, and Limewire is working better than ever - no more problems.