
If you have an artist name such as "Artist1 & Artist2" the tooltip will display as "Artist1 _Artist2". This behaviour is a result of using standard Microsoft tooltips and menu components where you use the & symbol to underline the next character to indicate the hot letter in a menu.
Please do some filtering before sending the string to the tooltip to prevent this from happening. I think you need to replace & with && to force the ampresand to display.