I solved the problem! The flikkering is caused by an old version of Java (Runtime Environment version 1.3.1_02) that LimeWire automatically downloads when installing the program.

I uninstalled the 1.3.1_02 version en downloaded and installed the newest version from the Sun Microsystems website (1.4.2_03). Guess what? No problems anymore.

Hopefully, this information will be helpfull for other users of LimeWire 3.8.6. Pro under XP who encounter the same problems.

Cheers!