Thanks fellas,

@ 6_pac - I've already tried disabling Ultrapeer capabilities. It didn't help a bit, as decreasing of number of downloads, too.

@ foolofthehill - I upgraded LW yesterday to v. 4.12.4. It didn't help. Same story continues.
.limeiwre was a typing error of course. Altough I believe that in 4.12.3 path was C:/Documents And Settings/your_username/.limewire, but I'll check it. I'll deinstall this version and revert to 4.12.3, to see.

What really confuse me is that my LW worked just fine until couple of days ago, and then it just broke...

This tips didn't help me, nevertheless great thanks to 6_pac & foolofthehill.